WO2024116837A1

WO2024116837A1 - Power-transmitting device, power-receiving device, wireless power transfer system, method for controlling power-transmitting device, and storage medium

Info

Publication number: WO2024116837A1
Application number: PCT/JP2023/040995
Authority: WO
Inventors: 元志村
Original assignee: キヤノン株式会社
Priority date: 2022-11-30
Filing date: 2023-11-14
Publication date: 2024-06-06
Also published as: JP2024078925A

Abstract

In order to carry out power transmission control and power reception control on the basis of a plurality of state detection results pertaining to a power-transmitting device and a power-receiving device, this wireless power transfer system comprises a power-transmitting device 100 and a power-receiving device 200. The power-transmitting device 100 wirelessly transfers electric power to the power-receiving device 200 by using a power-transmitting antenna. The power-transmitting device 100 executes a calibration process that is based on measurement of a physical quantity and carries out state detection using a measurement value. The power-transmitting device 100 determines whether it is necessary to execute the calibration process again, using information acquired when the measurement process is executed through first state detection and information acquired when the measurement process is executed through second state detection later than the first state detection, and reports the determined information to the power-receiving device 100.

Description

POWER TRANSMITTING APPARATUS, POWER RECEIVING APPARATUS, WIRELESS POWER TRANSMISSION SYSTEM, METHOD FOR CONTROLLING POWER TRANSMITTING APPARATUS, AND STORAGE MEDIUM

The present disclosure relates to a power transmission device, a power receiving device, a wireless power transmission system, a control method for a power transmission device, and a storage medium.

In a wireless power transmission system, a power transmitting device can wirelessly transmit power to a power receiving device placed on a charging stand or the like. If the power transmitting device or power receiving device determines that an abnormality has occurred, it performs control to prevent a decrease in power transmission efficiency and the generation of heat, etc.

Patent document 1 discloses a process for detecting a foreign object that has entered between the power transmitting coil and the power receiving coil, and a process for detecting a positional deviation between the power transmitting coil and the power receiving coil.

JP 2017-38509 A

In conventional technology, there is no established method for a power transmitting device to determine appropriate control based on a plurality of state detection results and to notify a power receiving device of a plurality of pieces of information related to the control.
The present disclosure has an object to provide a technique that enables power transmission control and power reception control based on a plurality of state detection results related to a power transmitting device and a power receiving device.

The power transmission device disclosed herein has a power transmission means for wirelessly transmitting power to a power receiving device using a power transmission antenna, a communication means for communicating with the power receiving device, a detection means for performing a measurement process of physical quantities related to the power transmission device and detecting the state of the power transmission device, and a control means for controlling the power transmission means and the measurement process. When the control means determines that the power receiving device should request the power transmission device to perform a measurement process again based on information acquired when a first state detection based on the measurement process is performed and information acquired when a second state detection based on a measurement process performed after the first state detection is performed, the control means controls the communication means to transmit to the power receiving device a signal having information on the state detection result related to the first or second state detection and a signal having information on the request to perform the measurement process again.

This disclosure provides a technology that enables power transmission control and power reception control based on multiple state detection results related to a power transmission device and a power receiving device.

FIG. 1 is a diagram illustrating a configuration example of a wireless power transmission system. FIG. 2 is a diagram illustrating a configuration example of a power transmitting device. FIG. 2 illustrates an example of the configuration of a power receiving device. This is an explanatory diagram illustrating an example of a threshold setting method for state detection using the Power Loss method. 1A and 1B are diagrams illustrating a Q-factor measurement method. 4 is a block diagram showing an example of a functional configuration of a control unit of the power transmitting device. FIG. 11 is a flowchart illustrating an example of processing performed by a power transmitting device. 11 is a flowchart illustrating an example of processing performed by a power receiving device. FIG. 11 is an explanatory diagram of state detection using a waveform decay method. FIG. 11 is a diagram illustrating an example of a process for performing wireless power transmission. FIG. 11 is an explanatory diagram showing an example of a threshold setting method in state detection by the waveform decay method. 13A and 13B are explanatory diagrams showing an example of a method for measuring an indicator of the coupling state between a power transmitting antenna and a power receiving antenna. FIG. 11 is an explanatory diagram showing an example of a threshold setting method in state detection by a coupling state indicator measurement method. 13 is a flowchart illustrating an example of processing performed by a power transmitting device in the second embodiment. 10 is a flowchart illustrating an example of processing performed by a power receiving device in the second embodiment. 11 is a sequence diagram illustrating an example of processing performed by a power transmitting device and a power receiving device. 13 is a flowchart illustrating an example of processing performed by a power transmitting device according to a third embodiment. 18 is a flowchart illustrating an example of processing following that shown in FIG. 17. FIG. 13 is a sequence diagram illustrating an example of processing by a power transmitting device and a power receiving device in the third embodiment.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the embodiments, a wireless charging system to which a wireless power transmission system is applied is shown. As an example, wireless power transmission based on the standard established by the Wireless Power Consortium, a standardization organization for wireless charging (hereinafter referred to as the WPC standard) will be described.

[First embodiment]
The present embodiment will be described with reference to Fig. 1 to Fig. 13. Fig. 1 is a diagram showing an example of the configuration of a wireless charging system.

This system includes a power transmission device 100, a power receiving device 200, and a charging stand 300. In the following, for the sake of simplicity, the power receiving device 200 may be referred to as RX and the power transmission device 100 as TX. The detailed configurations of TX and RX will be described later with reference to Figures 2 and 3.

RX is an electronic device that receives power from TX and charges its built-in battery while placed on the charging stand 300. TX is an electronic device that transmits power wirelessly to RX placed on the charging stand 300.

Because the charging stand 300 constitutes a part of the TX, hereinafter, when the RX is "placed on the charging stand 300," it may be said that the RX is "placed on the TX." The spatial range in which the RX can receive power from the TX is shown diagrammatically within the dotted line frame 400 in Figure 1.

RX and TX may have the functionality to execute applications other than the wireless charging function. For example, RX is a smartphone and TX is an accessory device for charging the battery of RX. However, this example is not limiting.

Next, an example of the configuration of the power transmission device 100 will be described with reference to FIG. 2. FIG. 2 is a functional block diagram showing an example of the configuration of the power transmission device 100 (TX). The TX has a control unit 101, a power supply unit 102, a power transmission unit 103, a first communication unit 104, a power transmission antenna (power transmission coil) 105, a memory 106, a resonant capacitor 107, a switch unit 108, a second communication unit 109, and a user interface unit 110.

Hereinafter, the user interface will be referred to as UI. In Figure 2, each functional block element is shown as a separate entity, but any number of functional block elements may be implemented within the same chip.

The control unit 101 controls the entire TX by executing a control program stored in the memory 106. The control unit 101 also controls power transmission, including communication for device authentication in the TX.

Furthermore, the control unit 101 can perform control to execute applications other than wireless power transmission. The control unit 101 is configured to include one or more processors such as a CPU (Central Processing Unit) or an MPU (Microprocessor Unit).

Alternatively, the control unit 101 may be configured with hardware such as an application specific integrated circuit (ASIC).

The control unit 101 may also be configured to include an array circuit such as an FPGA (Field Programmable Gate Array) compiled to execute a specified process. The control unit 101 can execute a process of storing information to be stored in the memory 106 during execution of various processes, and a time measurement process using a timer (not shown).

The power supply unit 102 supplies power to each functional block element. The power supply unit 102 includes, for example, a power supply connection circuit to a commercial power source and a battery. The battery is charged with power supplied from the commercial power source.

The power transmission unit 103 converts the DC or AC power input from the power supply unit 102 into AC power in the frequency band used for wireless power transmission, and inputs the AC power to the power transmission antenna 105, thereby generating electromagnetic waves for the RX to receive power.

For example, the power transmission unit 103 includes an inverter and converts the DC voltage supplied by the power supply unit 102 into an AC voltage using a switching circuit with a half-bridge or full-bridge configuration. The power transmission unit 103 includes multiple FETs (Field Effect Transistors) that form a bridge, and a gate driver that controls the ON/OFF of the multiple FETs.

The power transmitting unit 103 controls the intensity of the electromagnetic waves (power transmission power) to be output by adjusting the voltage (power transmission voltage) or current (power transmission current), or both, input to the power transmitting antenna 105.

The strength of the electromagnetic waves (the magnitude of the transmitted power) is controlled by the magnitude of the transmitted voltage or current. Alternatively, the power transmitting unit 103 controls the strength of the electromagnetic waves to be output (the transmitted power) by adjusting the voltage or current, or both, input to the inverter possessed by the power transmitting unit 103. The voltage input to the inverter is hereinafter referred to as the inverter input voltage.

The current input to the inverter is hereinafter referred to as the inverter input current. The strength of the electromagnetic waves is controlled by the magnitude of the inverter input voltage or inverter input current. Alternatively, the power transmission unit 103 controls the strength of the electromagnetic waves to be output (transmitted power) by adjusting the voltage or current, or both, output from the inverter possessed by the power transmission unit 103.

The voltage output from the inverter is hereinafter referred to as the inverter output voltage. The current output from the inverter is hereinafter referred to as the inverter output current. The strength of the electromagnetic waves is controlled by the magnitude of the inverter output voltage or inverter output current.

The power transmission unit 103 performs output control of the power of the AC frequency electromagnetic waves so that the power transmission by the power transmission antenna 105 is started or stopped, or the intensity of the electromagnetic waves to be output is controlled based on an instruction signal from the control unit 101.

Furthermore, the power transmitting unit 103 is assumed to have a power supply capacity sufficient to output 15 watts (W) of power to the charging unit (206 in FIG. 3) of the power receiving device 200 that complies with the WPC standard.

The first communication unit 104 is connected to the control unit 101 and the power transmission unit 103, and communicates with the RX for power transmission control based on the WPC standard. The first communication unit 104 performs frequency shift keying of the electromagnetic waves output from the power transmission antenna 105, and transmits information to the RX to perform communication.

The first communication unit 104 also demodulates the electromagnetic waves transmitted from the power transmitting antenna 105 that were modulated by the RX, and acquires the information transmitted by the RX. Communication by the first communication unit 104 is performed by superimposing a communication signal on the electromagnetic waves transmitted from the power transmitting antenna 105.

In addition to the control program, the memory 106 can store information related to the TX and RX states. Information related to the TX and RX states includes the transmission power value, the receiving power value, etc.

Information regarding the TX state is acquired by the control unit 101. Information regarding the RX state is acquired by the RX control unit (201 in Fig. 3) and can be received by the first communication unit 104 or the second communication unit 109 described below.

The switch unit 108 is connected in parallel to the series circuit of the resonant capacitor 107 and the power transmission antenna 105. The control unit 101 transmits a control signal to the switch unit 108 to control its ON/OFF state.

The power transmitting antenna 105 is connected to a resonant capacitor 107. When the switch unit 108 is turned on and short-circuited by a control signal from the control unit 101, the power transmitting antenna 105 and the resonant capacitor 107 form a series resonant circuit and resonate at a specific frequency fA.

At this time, current flows through the closed circuit formed by the power transmitting antenna 105, resonant capacitor 107, and switch unit 108. Meanwhile, when the switch unit 108 is turned off by a control signal from the control unit 101 and the circuit is opened, power is supplied from the power transmitting unit 103 to the power transmitting antenna 105 and resonant capacitor 107.

The second communication unit 109 is connected to the control unit 101, and communicates with the RX using a standard different from the WPC standard. For example, the second communication unit 109 communicates with the RX (the second communication unit 212 in FIG. 3) using an antenna different from the power transmission antenna 105.

These include wireless LAN (Local Area Network), Bluetooth (registered trademark) Low Energy (BLE), and NFC (Near Field Communication).

The frequency band used when transmitting power from the power transmitting antenna 105 is different from the frequency band used by the second communication unit 109 for communication.

Regarding communication between TX and RX, TX may selectively use one of multiple communication standards to communicate with RX. The following communication formats are possible:

Communication based on the first standard (WPC standard) between the first communication unit 104 of the TX and the first communication unit 204 of the RX (FIG. 3).
Communication based on a second standard (a standard other than the WPC standard) between the second communication unit 109 of the TX and the second communication unit 212 of the RX (FIG. 3).

The UI unit 110 is connected to the control unit 101 and performs various outputs to the user. The various outputs include screen display, blinking or color changes of LEDs (Light Emitting Diodes), audio output from a speaker, vibration of the TX main unit, and other operations. The UI unit 110 is realized by an LCD panel, a speaker, a vibration motor, etc.

Next, an example of the configuration of the power receiving device 200 will be described with reference to FIG. 3. FIG. 3 is a block diagram showing an example of the configuration of the power receiving device 200 (RX). The RX has a control unit 201, a UI unit 202, a power receiving unit 203, a first communication unit 204, a power receiving antenna 205, a charging unit 206, a battery 207, and a memory 208.

The RX further has a first switch unit 209, a second switch unit 210, a resonant capacitor 211, a second communication unit 212, and a third switch unit 213. In this embodiment, an example is shown in which the functional block elements in FIG. 3 are individual elements, but multiple functional block elements may be realized as one hardware module.

The control unit 201 controls each functional block element of the RX by executing a control program stored in the memory 208. Furthermore, the control unit 201 can perform control to execute applications other than wireless power transmission.

The control unit 201 is configured to include one or more processors such as a CPU or MPU. In addition, the control unit 201 can control the entire RX (e.g., the entire smartphone) in cooperation with the OS (Operating System) that it is running.

Alternatively, the control unit 201 may be configured with hardware such as an ASIC, or may include an array circuit such as an FPGA compiled to execute a specified process. The control unit 201 stores information to be stored during execution of various processes in the memory 208, and is also capable of executing timing processes using a timer (not shown).

The UI unit 202 is connected to the control unit 201, and performs various outputs to the user. The various outputs include screen display, blinking or color changes of LEDs, audio output from a speaker, vibration of the RX main unit, and other operations. The UI unit 202 is realized by an LCD panel, a speaker, a vibration motor, etc.

The power receiving unit 203 receives AC power (AC voltage and AC current) generated by electromagnetic induction based on electromagnetic waves radiated from the TX power transmitting antenna 105 via the power receiving antenna (power receiving coil) 205.

Then, the power receiving unit 203 converts the AC power into DC or AC power of a predetermined frequency and supplies the power to the charging unit 206. The charging unit 206 charges the battery 207. The power receiving unit 203 includes a rectification unit (rectifier, rectification circuit) and a voltage control unit that are necessary to supply power to the load in the RX.

The rectifier converts the AC voltage and AC current received from the power transmitting antenna 105 via the power receiving antenna 205 into a DC voltage and DC current. Hereinafter, this DC voltage is referred to as the rectifier output voltage.

This DC current will be referred to as the rectifier output current below. The voltage control unit converts the level of the rectifier output voltage to a predetermined level. The predetermined level is a DC voltage level at which the control unit 201 and the charging unit 206, etc. can operate.

The power receiving unit 203 supplies power for charging the battery 207 from the charging unit 206. The power receiving unit 203 is assumed to have a power supply capacity sufficient to output 15 watts of power to the charging unit 206.

The first communication unit 204 communicates with the first communication unit 104 of the TX for power reception control based on the WPC standard. The first communication unit 204 is connected to the power receiving antenna 205 and the control unit 201, and demodulates the electromagnetic waves input from the power receiving antenna 205 to obtain the information transmitted from the TX.

The first communication unit 204 performs load modulation or amplitude modulation on the input electromagnetic waves and superimposes a signal related to the information to be transmitted to the TX onto the electromagnetic waves, thereby communicating with the TX.

In addition to the control program, the memory 208 stores information about the status of the TX and RX. Information about the status of the RX is acquired by the control unit 201. Information about the status of the TX is acquired by the control unit 101 of the TX, and can be received by the first communication unit 204 or the second communication unit 212.

The second communication unit 212 is connected to the control unit 201, and communicates with the TX using a standard different from the WPC standard. For example, the second communication unit 212 communicates with the TX (the second communication unit 109 in FIG. 2) using an antenna different from the receiving antenna 205.

　Standards other than the WPC standard are as described above, and for communication between the TX and RX, the RX can selectively use one of multiple communication standards to communicate with the TX.

The frequency band used when receiving power by the receiving antenna 205 is different from the frequency band used by the second communication unit 212 for communication.

The first switch unit 209 is provided between the charging unit 206 and the battery 207, and is controlled by the control unit 201. The first switch unit 209 has a function of controlling whether or not the power received by the power receiving unit 203 is to be supplied to the battery 207, and a function of controlling the size of the load.

When the control unit 201 turns the first switch unit 209 to the OFF state and opens it, the power received by the power receiving unit 203 is not supplied to the battery 207. When the control unit 201 turns the first switch unit 209 to the ON state and shorts it, the power received by the power receiving unit 203 is supplied to the battery 207.

In the example of FIG. 3, the first switch unit 209 is disposed between the charging unit 206 and the battery 207, but the first switch unit 209 may be disposed between the power receiving unit 203 and the charging unit 206.

Alternatively, the first switch unit 209 may be disposed between the power receiving unit 203 and the closed circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210. In this case, the first switch unit 209 has a function of controlling whether or not the power received by the power receiving antenna 205 is supplied to the power receiving unit 203.

In the example of FIG. 3, the first switch unit 209 is shown as a single functional block element, but it is possible to realize the first switch unit 209 as part of the charging unit 206 or the power receiving unit 203.

Furthermore, the first switch unit 209 is not limited to being inserted in series between the charging unit 206 and the battery 207, but may be inserted in parallel between the charging unit 206 and the battery 207.

In this case, when the control unit 201 turns the first switch unit 209 to the OFF state and opens it, the power received by the power receiving unit 203 is supplied to the battery 207. When the control unit 201 turns the first switch unit 209 to the ON state and shorts it, the power received by the power receiving unit 203 is not supplied to the battery 207.

On the input side of the power receiving unit 203, the second switch unit 210 is connected in parallel with the resonant capacitor 211. The resonant capacitor 211 is connected to the power receiving antenna 205 via the third switch unit 213.

The second switch unit 210 and the third switch unit 213 are controlled by the control unit 201. The third switch unit 213 has a function of controlling whether or not the terminal of the power receiving antenna 205 is opened.

When the control unit 201 turns the third switch unit 213 to the OFF state, the terminal of the power receiving antenna 205 is in an open state. When the control unit 201 turns the third switch unit 213 to the ON state, the power receiving antenna 205 is connected to the power receiving unit 203 via the resonant capacitor 211.

When the control unit 201 turns the third switch unit 213 to the ON state and the second switch unit 210 is turned ON and short-circuited, the receiving antenna 205 and the resonant capacitor 211 form a series resonant circuit and resonate at a specific frequency fB.

Current flows through the closed circuit formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch section 210, and no current flows through the power receiving section 203. When the second switch section 210 is turned OFF and the circuit is opened, the power received by the power receiving antenna 205 and the resonant capacitor 211 is supplied to the power receiving section 203.

Note that, without being limited to the example of FIG. 3, the second switch section 210 may be disposed between the power receiving antenna 205 and the resonant capacitor 211. When the third switch section 213 is in the ON state and the second switch section 210 is in the ON state, the terminals of the power receiving antenna 205 are shorted. The third switch section 213 may also be disposed between the resonant capacitor 211 and the power receiving section 203.

In this system, wireless power transmission based on the WPC standard is performed between the transmitting antenna 105 and the receiving antenna 205. In the WPC standard, the amount of power guaranteed when the receiving device 200 receives power from the transmitting device 100 is specified by a power called Guaranteed Load Power (hereinafter referred to as "GP").

The value of GP is expressed as the GP value or GP. For example, GP indicates a power value that guarantees output to the load of the power receiving device 200 even if the coupling between the power receiving antenna 205 and the power transmitting antenna 105 weakens due to a change in the positional relationship between the power receiving device 200 and the power transmitting device 100, causing a decrease in power transmission efficiency.

The load of the power receiving device 200 is the charging unit 206, the battery 207, etc. in FIG. 3, and the GP value corresponds to the amount of power guaranteed to be output from the power receiving unit 203. Alternatively, the GP value corresponds to the amount of power guaranteed to be output from the rectification unit of the power receiving unit 203.

For example, let us assume that the GP value is 5 (watts) and the positional relationship between the power receiving antenna 205 and the power transmitting antenna 105 changes. In this case, even if the power transmission efficiency decreases, the power transmitting device 100 performs power transmission control so that it can output 5 watts to the load of the power receiving device 200.

GP is determined by negotiation between the power transmitting device 100 and the power receiving device 200. This embodiment can be applied to any configuration in which power is transmitted and received at a power determined by mutual negotiation between the power transmitting device and the power receiving device, not limited to GP.

In addition, assume that an object is present near the power transmitting device 100 when transmitting power from the power transmitting device 100 to the power receiving device 200. In this case, the object is an object that may affect the power transmission from the power transmitting device 100 to the power receiving device 200, and is an object (foreign object) different from the power receiving device 200. There is a possibility that the electromagnetic waves used for power transmission may affect the foreign object, causing an increase in temperature or destruction of the foreign object.

In this disclosure, a foreign object is, for example, a paperclip or an IC card. A foreign object is neither a part of a power receiving device or a product in which the power receiving device is incorporated, nor a part of a power transmitting device or a product in which the power transmitting device is incorporated, but is an object that can generate heat when exposed to a power signal transmitted by a power transmitting antenna.

　Power receiving devices and objects that are an integral part of the product in which the power receiving device is incorporated, or power transmitting devices and objects that are an integral part of the product in which the power transmitting device is incorporated, are not considered foreign objects.

The WPC standard prescribes a method for preventing the occurrence of temperature rise and destruction of a foreign object by stopping power transmission when a foreign object is present. Specifically, the power transmission device 100 is capable of detecting the presence of a foreign object on the charging stand 300.

The power loss method is a method for detecting a foreign object based on the difference between the transmitted power in the power transmitting device 100 and the received power in the power receiving device 200. The Q-factor measurement method is a method for detecting a foreign object based on a change in the quality factor (Q-factor, quality coefficient, Q-factor) of the power transmitting antenna 105 (power transmitting coil) in the power transmitting device 100.

The Q-factor measurement method is a method for detecting foreign objects by detecting changes in the quality factor (Q-factor, quality coefficient, Q-factor) of the resonant circuit including the power transmitting antenna 105 (power transmitting coil) and the resonant capacitor 107 in the power transmitting device 100.

However, the foreign objects that the power transmission device 100 detects are not limited to objects that are present on the charging stand 300. The power transmission device 100 is capable of detecting foreign objects that are located in the vicinity of the power transmission device 100.

For example, the power transmitting device 100 can detect a foreign object located within the range where power can be transmitted. Hereinafter, the Quality Factor of the power transmitting antenna 105 and the Quality Factor of the resonant circuit including the power transmitting antenna 105 and the resonant capacitor 107 will be referred to as the Quality Factor related to the power transmitting antenna 105.

With reference to Figure 4, foreign object detection based on the Power Loss method defined in the WPC standard will be described. In Figure 4, the horizontal axis represents the transmitted power of the power transmitting device 100, and the vertical axis represents the received power of the power receiving device 200.

On the graph line indicated by the straight line segment 1002, point 1000 corresponds to the first transmitted power value Pt1 and the first received power value Pr1, and point 1001 corresponds to the second transmitted power value Pt2 and the second received power value Pr2. On the graph line, point 1003 corresponds to the third transmitted power value Pt3 and the third received power value Pr3. The foreign object to be detected is a conductive metal piece or the like.

First, the power transmitting device 100 transmits power to the power receiving device 200 at a first transmission power value Pt1, and the power receiving device 200 receives power at a first reception power value Pr1. Hereinafter, this state is referred to as a light load state.

The power transmitting device 100 stores the first transmission power value Pt1. At this time, the power receiving device 200 performs load control so that the power received is the minimum power. Alternatively, the power receiving device 200 performs load control so that the power received is within a predetermined range or is equal to or less than a threshold.

Here, in "power within a predetermined range" or "power below a threshold," the "power" refers to a power that is approximately 10% of the Reference Power described below.

The power receiving device 200 may also disconnect the load from the power receiving antenna 205 so that the received power is not supplied to the load (such as the charging unit 206 or the battery 207 in FIG. 3). Alternatively, the power receiving device 200 may control the load so that a predetermined amount of power is supplied to the load.

These can be achieved by controlling the first switch unit 209. Next, the power receiving device 200 notifies the power transmitting device 100 of the first received power value Pr1. The power transmitting device 100, which has received a signal relating to the first received power value Pr1 from the power receiving device 200, calculates the power loss between the power transmitting device 100 and the power receiving device 200.

The power loss at this time is Pt1-Pr1 (=Ploss1). A calibration point (hereafter abbreviated as CP) 1000 can be generated that indicates the correspondence between Pt1 and Pr1.

Then, the power transmitting device 100 changes the transmission power value to the second transmission power value Pt2 and transmits power to the power receiving device 200, and the power receiving device 200 receives power at the second receiving power value Pr2. Hereinafter, this state is referred to as the Connected Load state.

The power transmitting device 100 stores the second transmission power value Pt2. At this time, the power receiving device 200 performs load control so that the power received is the maximum power. Here, the "maximum power" is a power value close to the Reference Power described later.

Alternatively, the power receiving device 200 performs load control so that the received power is within a predetermined range or is equal to or greater than a threshold. For example, the power receiving device 200 connects the power receiving antenna 205 to a load so that the received power is supplied to the load.

These can be achieved by controlling the first switch unit 209. Next, the power receiving device 200 notifies the power transmitting device 100 of the second received power value Pr2. The power transmitting device 100, which has received a signal relating to the second received power value Pr2 from the power receiving device 200, calculates the power loss between the power transmitting device 100 and the power receiving device 200.

The power loss at this time is Pt2 - Pr2 (= Ploss2). CP1001 can be generated, which shows the correspondence between Pt2 and Pr2.

The power transmitting device 100 performs linear interpolation between CP1000 and CP1001 to generate a line segment 1002. The line segment 1002 shows the relationship between the transmitted power and the received power in a state in which no foreign object is detected to exist near the power transmitting device 100 and the power receiving device 200 (hereinafter referred to as the first detection state).

Based on the line segment 1002, the power transmission device 100 can estimate the power value that the power receiving device 200 will receive when transmitting power at a specified transmission power in the first detection state. For example, assume that the power transmission device 100 transmits power at a third transmission power value Pt3. In this case, the power transmission device 100 can estimate the third received power value Pr3 that the power receiving device 200 will receive from a point 1003 on the line segment 1002 that corresponds to Pt3.

As described above, the power loss between the power transmission device 100 and the power receiving device 200 according to the load can be calculated based on multiple combinations of the transmission power value of the power transmission device 100 and the reception power value of the power receiving device 200 measured while changing the load.

In addition, the power loss between the power transmission device 100 and the power receiving device 200 according to all loads can be estimated by interpolating multiple combinations of the transmitted power value and the received power value. The calibration process performed by the power transmission device 100 and the power receiving device 200 in this manner in order for the power transmission device 100 to obtain combinations of the transmitted power value and the received power value is called "calibration process using the power loss method."

The calibration process is abbreviated as CAL process. The power transmitting device 100 and the power receiving device 200 can execute the CAL process multiple times. CAL process that is executed again after the CAL process has been executed once is hereinafter referred to as "Recalibration process of the Power Loss method." The recalibration process is abbreviated as RECAL process.

It is assumed that after the CAL process of the Power Loss method, the power transmitting device 100 actually transmits power to the power receiving device 200 at the third transmission power value Pt3, and the power transmitting device 100 receives a signal related to the received power value Pr3 ^* from the power receiving device 200.

The signal relating to this received power value Pr3 ^* is a Received Power Data packet (mode 0) defined in the WPC standard, but other messages may also be used.

Hereinafter, the Received Power Data packet (mode 0) is denoted as RP0. RP0 includes the value of the received power value Pr3 ^* . The power transmitting device 100 subtracts the received power value Pr3 ^* received from the power receiving device 200 from the received power value Pr3 in the first detection state to calculate Pr3-Pr3 ^* (=Plus_FO).

When a foreign object is present near the power transmitting device 100 and the power receiving device 200, Ploss_FO can be estimated as the power consumed by the foreign object, i.e., the power loss. Hereinafter, the state in which the presence of a foreign object is detected near the power transmitting device 100 and the power receiving device 200 is referred to as the second detection state.

In the second detection state, the power transmission device 100 compares the power loss Ploss_FO that would have been consumed by the foreign object with a predetermined threshold value. If the value of the power loss Ploss_FO exceeds the threshold value, the power transmission device 100 can determine that a foreign object is present.

Alternatively, the power transmitting device 100 obtains the third received power value Pr3 in the first detection state from the power receiving device 200, and calculates the power loss Pt3-Pr3 (=Ploss3) between the power transmitting device 100 and the power receiving device 200 in advance.

Next, the power transmitting device 100 acquires the received power value Pr3 ^* from the power receiving device 200 in the second detection state, and calculates the power loss Pt3-Pr3 ^* (=Ploss3 ^* ) between the power transmitting device 100 and the power receiving device 200 in the second detection state.

Then, the power transmitting device 100 can estimate the power loss Ploss_FO using Plus3 ^* -Plus3.

As described above, there are two methods for calculating Ploss_FO in the second detection state.
A first method of calculating Ploss_FO from Pr3-Pr3 ^* .
A second method for calculating Plus_FO from Plus3 ^* -Plus3.

In this embodiment, the second method is basically described, but the contents of this embodiment can also be applied to the first method.

Next, referring to Figure 5, we will explain foreign object detection based on the Q-factor measurement method defined in the WPC standard. Figure 5 (A) is a schematic circuit diagram for explaining the method of measuring the Quality Factor (Q-factor, quality coefficient, Q-factor) using the Q-factor measurement method.

The AC power source 901 is a power source that outputs the AC power generated by the power transmission unit 103 of the TX. The power transmission antenna 902 corresponds to the power transmission antenna 105, and the capacitor 903 corresponds to the resonant capacitor 107.

The power transmitting antenna 902 and the capacitor 903 are connected in series. The voltage value V8 is a voltage value of a predetermined frequency generated by the power transmitting unit 103 for operating the wireless power transmission system. The voltage value V9 is a voltage value applied to the power transmitting antenna 902.

Here, the TX is assumed to be able to change the frequency related to the voltage value. Furthermore, the voltage values V8 and V9 are the voltage values that the TX measures when it transmits an Analog Ping (hereafter referred to as AP) or a Digital Ping (hereafter referred to as DP) to the RX.

Note that since voltage values V8 and V9 are AC voltage values, their effective values (RMS) may also be used.

Figure 5 (B) shows an example of the measurement results of V9/V8 versus frequency, with a peak at 100 kHz. The horizontal axis is the frequency axis, and the vertical axis represents the voltage ratio "V9/V8." V9/V8 represents the quality factor associated with the power transmitting antenna 902.

Since V9/V8 corresponds to the quality factor of the resonant circuit including the power transmitting antenna 902 and the resonant capacitor 903, its value changes when an object is placed near the power transmitting antenna 902.

The change in Quality Factor differs depending on whether no object is placed on the TX, whether an RX is placed on the TX, whether a foreign object (such as a metal piece) is placed on the TX, or whether an RX and a foreign object are placed on the TX.

In the Negotiation phase, TX receives a FOD Status Data packet signal from RX. The FOD Status Data packet includes a Reference Quality Factor Value and a Reference Resonance Frequency Value.

The Reference Quality Factor Value is the Quality Factor that can be measured at the terminals of the transmitting antenna of the test TX when the RX is placed on the test TX and there are no foreign objects nearby.

The Reference Resonance Frequency Value is the resonant frequency calculated from the inductance value that can be measured at the terminal of the transmitting antenna of the test TX when the RX is placed on the test TX and there is no foreign object nearby.

In the Q-value measurement method, a threshold is set based on the Reference Quality Factor Value. Foreign objects are detected by comparing this threshold with the Quality Factor calculated from the measured V9/V8.

Alternatively, a threshold value is set based on the Reference Resonance Frequency Value. Foreign objects are detected by comparing this threshold value with the resonance frequency obtained by measuring V9/V8.

The RX and TX in this embodiment communicate for power transmission and reception control based on the WPC standard. The WPC standard specifies multiple phases, including a Power Transfer phase in which power transmission is performed, and one or more phases before power transmission.

In each phase, communication is carried out for the necessary power transmission and reception control. For example, foreign object detection using the Power Loss method is performed in the Power Transfer phase based on data obtained in the Calibration phase. In addition, foreign object detection using the Q-value measurement method is performed before power transmission (before sending DP and in the Negotiation phase or Renegotiation phase).

The phases before power transmission in the WPC standard include the Selection phase, the Ping phase, and the Identification and Configuration phase (Configuration phase).

There are also a Negotiation phase and a Calibration phase. Below, the Identification and Configuration phase is referred to as the I&C phase. The processing of each phase is explained below.

In the Selection phase, the TX transmits the AP intermittently and detects that an object has been placed on the charging base of the TX. For example, it detects that an RX or a piece of conductor has been placed on the charging base. The TX detects the voltage value or current value, or both, of the transmitting antenna 105 when the AP is transmitted.

If the voltage value falls below a threshold or if the current value exceeds a threshold, the TX determines that an object is present and transitions to the Ping phase. Alternatively, if the Quality Factor calculated from the voltage value or current value satisfies a predetermined condition, the TX determines that an object is present and transitions to the Ping phase.

In the Ping phase, the TX transmits a DP with a higher power than the AP. The power of the DP is sufficient to start the control unit of the RX placed on the TX. The RX notifies the TX of the received voltage value.

In this way, by receiving a response from the RX that received the DP, the TX recognizes that the object detected in the Selection phase is the RX. When the TX is notified of the received voltage value from the RX, it transitions to the I&C phase. In addition, before transmitting the DP, the TX measures the Quality Factor associated with the transmitting antenna 105, for example, using the AP.

These measurement results are used when performing foreign object detection processing using the Q-value measurement method. Note that, depending on the version of the WPC standard, the above-mentioned Selection phase may be included as part of the above-mentioned Ping phase and may be called the Ping phase.

In the I&C phase, the TX identifies the RX and obtains device configuration information (capability information) from the RX. The RX transmits the ID Data packet and Configuration Data packet signals.

The ID Data packet contains the RX's identifier information, and the Configuration Data packet contains the RX's device configuration information (capability information). When the TX receives the ID Data packet and Configuration Data packet signals, it responds with an acknowledgement (positive response ACK).

Then, the I&C phase ends. Note that depending on the version of the WPC standard, the I&C phase may also be called the Configuration phase. In the Negotiation phase, the GP value is determined based on the GP value requested by the RX and the power transmission capability of the TX.

The TX also receives a FOD Status Data packet from the RX, which includes the above Reference Quality Factor Value and Reference Resonance Frequency Value.

In the Q-value measurement method, the presence or absence of foreign matter is determined based on a threshold value based on the Reference Quality Factor Value and the Reference Resonance Frequency Value.

The TX performs foreign object detection processing using the Q-value measurement method in response to a request from the RX. The WPC standard also prescribes a method of transitioning to the Power Transfer phase once, and then performing processing similar to that of the Negotiation phase again at the request of the RX. The phase in which this processing is performed after transitioning from the Power Transfer phase is called the Renegotiation phase.

In the calibration phase, the CAL process using the Power Loss method is performed. In addition, the RX notifies the TX of a specified received power value, and the TX makes adjustments to transmit power efficiently.

The specified received power value is, for example, the received power value in a light load state (Light Load state) or a connected load state (Connected Load state). The received power value notified to the TX is used for foreign object detection processing using the Power Loss method.

In the Power Transfer phase, the TX and RX control the start and continuation of power transmission, as well as error processing and stopping of power transmission due to full charge. The TX and RX handle the communication processing for this power transmission and reception control.

For example, using the transmitting antenna 105 and the receiving antenna 205 used when performing wireless power transmission based on the WPC standard, communication is performed by superimposing a signal on the electromagnetic waves transmitted from the transmitting antenna 105 or the receiving antenna 205. The range in which communication based on the WPC standard between the TX and the RX is possible is the same as the range in which the TX can transmit power.

Note that depending on the version of the WPC standard, the Calibration phase mentioned above may also be called the Power Transfer phase as part of the Power Transfer phase mentioned above.

Next, the function of the control unit of the TX will be described with reference to FIG. 6. FIG. 6 is a block diagram showing an example of the functional configuration of the control unit 101 of the power transmitting device 100 (TX). The control unit 101 has a communication control unit 301, a power transmission control unit 302, a measurement unit 303, a setting unit 304, and a state detection unit 305. The communication control unit 301 controls communication with the RX based on the WPC standard via the first communication unit 104, or controls communication with the RX via the second communication unit 109.

The power transmission control unit 302 controls the power transmission unit 103 to control the power transmission to the RX. The measurement unit 303 measures a waveform attenuation index, which will be described later. The measurement unit 303 also measures the power transmitted to the RX via the power transmission unit 103, and measures the average transmitted power per unit time.

The measurement unit 303 also measures the Quality Factor associated with the power transmitting antenna 105. The measurement unit 303 also measures the temperature using temperature sensors arranged at multiple locations on the power transmitting device 100. The measurement unit 303 also measures a quantity (e.g., a coupling coefficient) that represents the electromagnetic coupling state between the power transmitting antenna 105 and the power receiving antenna 205.

The setting unit 304 calculates and sets the threshold value for detecting foreign objects in the Q-value measurement method and the threshold value for detecting foreign objects in the Power Loss method using the method described above. The setting unit 304 also sets the threshold value for detecting foreign objects in the waveform attenuation method using a method described later.

The setting unit 304 also calculates and sets a threshold value for detecting foreign objects or a threshold value for detecting misalignment between TX and RX, based on the coupling coefficient between the transmitting antenna 105 and the receiving antenna 205 measured by the measuring unit 303, for example.

The setting unit 304 also calculates and sets a threshold value for detecting a foreign object or a threshold value for detecting a positional deviation between TX and RX, for example, based on the temperature of the power transmitting device measured by the measurement unit 303. The setting unit 304 also calculates and sets a threshold value for detecting a foreign object or a threshold value for detecting a positional deviation between TX and RX, for example, based on the current value of the power transmitting antenna 105 measured by the measurement unit 303.

The status detection unit 305 detects the status of TX and RX. For example, the status detection unit 305 detects a foreign object between TX and RX, and also detects a positional deviation between the transmitting antenna 105 and the receiving antenna 205.

More specifically, state detection processing is possible based on the power loss method, the Q-value measurement method, and the waveform attenuation method. State detection processing is also possible based on the temperature measured by the power transmission device 100, the electromagnetic coupling state (e.g., the coupling coefficient) between the power transmission antenna 105 and the power receiving antenna 205, and the current value of the power transmission antenna 105 measured by the power transmission device 100.

The status detection unit 305 can detect foreign objects and positional misalignment between the power transmitting antenna 105 and the power receiving antenna 205 using other methods. For example, in a TX equipped with an NFC communication function, the status detection unit 305 performs status detection processing using a function for detecting a counterpart device according to the NFC standard.

In addition to detecting the presence or absence of a foreign object and the electromagnetic coupling state between the power transmitting antenna and the power receiving antenna, the state detection unit 305 can also detect state changes on the TX. For example, the state detection unit 305 can detect an increase or decrease in the number of power receiving devices on the TX.

The setting unit 304 sets a threshold value that serves as a reference for determining the presence or absence of a foreign object when the TX performs status detection. Status detection is, for example, status detection based on the power loss method, the Q value measurement method, the waveform attenuation method, or status detection based on the temperature measured in the power transmission device 100.

The state detection is based on the coupling coefficient between the power transmitting antenna 105 and the power receiving antenna 205, and based on the current value of the power transmitting antenna 105 measured by the power transmitting device 100. The setting unit 304 can set a judgment threshold value required for state detection processing using other methods.

The state detection unit 305 can perform foreign object detection processing and positional deviation detection processing between the power transmitting antenna 105 and the power receiving antenna 205 based on the threshold value set by the setting unit 304 and the measurement results by the measurement unit 303.

For example, the state detection unit 305 can acquire data such as the waveform attenuation index, the transmission power, and the Quality Factor as the measurement results of the measurement unit 303. The state detection unit 305 can acquire data such as the temperature measured in the power transmission device 100, the coupling coefficient between the power transmission antenna 105 and the power receiving antenna 205, and the current value of the power transmission antenna 105 measured in the power transmission device 100 as the measurement results of the measurement unit 303.

The processes performed by the communication control unit 301, power transmission control unit 302, measurement unit 303, setting unit 304, and state detection unit 305 shown in FIG. 6 can be realized using a program executed by a CPU or the like included in the control unit 101.

Each process is executed in parallel according to an independent program, with synchronization between the programs achieved by event processing, etc. However, two or more of these processes may be incorporated into the processing of a single program.

Next, an example of the flow of processing related to power transmission and reception control executed by the TX and RX will be described. FIG. 7 is a flowchart showing an example of power transmission control processing executed by the TX. This processing is realized, for example, by the control unit 101 of the TX executing a program read from the memory 106.

This process may also be executed when the power of the TX is turned on, when the user of the TX inputs an instruction to start a wireless power transmission application, or when the TX is connected to a commercial power source and receives power. This process may also be started by some other trigger.

In S1201 of FIG. 7, the TX executes the processes defined as the Selection phase and Ping phase of the WPC standard, and waits for the RX to be placed on it. The TX repeatedly transmits the AP of the WPC standard intermittently, and detects objects that are present within the power transmission range.

For example, the TX can detect that an RX, a conductor piece, etc. has been placed on the charging stand 300. When the TX detects that an object is present within the power transmission range, it transmits a DP.

If there is a specified response to the DP, the TX determines that the detected object is the RX and that the RX has been placed on the charging stand 300. Here, the "specified response" is the Signal Strength (SIG) data packet sent by the RX.

This packet contains a Signal Strength Value that indicates the signal strength of the signal (DP) received by the RX. The Signal Strength Value is calculated from the voltage (rectifier output voltage) output by the rectifier (rectifier, rectifier circuit) of the power receiving unit 203 that is measured by the RX.

Alternatively, the Signal Strength Value is calculated from the voltage of an open circuit including the receiving antenna 205 (open circuit voltage) measured by the RX, or the received power value measured by the RX. In addition, the TX measures the Quality Factor related to the transmitting antenna 105 before transmitting the DP. This measurement result is used when performing foreign object detection processing using the Q-value measurement method.

After the placement of the RX is detected, in S1202 the TX obtains identification information from the RX through communication in the I&C phase defined by the WPC standard. In the I&C phase, the RX transmits an Identification Packet (ID Packet) to the TX.

The ID packet contains the Manufacturer Code and Basic Device ID, which are identification information for each individual RX, as well as information that can identify the version of the WPC standard that is supported.

Furthermore, the RX sends a Configuration Data Packet to the TX. The Configuration Data Packet contains the following RX capability information:

- Information that makes it possible to identify the version of the WPC standard that the RX supports.
- Maximum Power Value or Reference Power, which is a value that specifies the maximum power the RX can supply to the load.
Information indicating whether the RX has a WPC standard Negotiation function.
A parameter used in frequency shift keying, which is a communication modulation method used when TX transmits information to RX.

When the TX receives the above packet from the RX, it sends an acknowledgement ACK to the RX, and the I&C phase ends. Note that the TX may obtain the identification information of the RX by a method other than the I&C phase communication of the WPC standard.

The identification information for each individual RX may be a Wireless Power ID. Alternatively, it may be any other identification information capable of identifying an individual RX, such as a Bluetooth (registered trademark) Address (hereinafter, referred to as "BD_ADDR") that is unique to the second communication unit 212 of the RX.

BD_ADDR is an 8-byte address used in BLE. BD_ADDR is a public address defined in the BLE standard that indicates, for example, the manufacturer of the RX or individual identification information of the BLE communication function (the function of the second communication unit 212). BD_ADDR may also be a random address.

Next, in S1203, the TX negotiates with the RX to determine the GP based on the request from the RX and the power transmission capability of the TX's own device. In S1203, communication is performed in the negotiation phase of the WPC standard.

First, the RX notifies the TX of the requested GP value by sending a Specific Request to the TX. The TX determines whether to accept the request based on the power transmission capacity of its own device and other conditions.

If TX accepts the request, it sends a positive acknowledgement ACK to RX, and if it does not accept the request, it sends a negative acknowledgement NACK or NAK to RX. The determined GP value is the value requested by RX when TX accepts the request from RX.

If the TX does not accept the request from the RX, the GP value becomes a predetermined value (e.g., 5 watts) defined in the WPC standard. Alternatively, if the TX acquires information indicating that the RX does not support the negotiation phase (e.g., S1302 described below), it does not perform communication in the negotiation phase and sets the GP value to a predetermined value. The predetermined value is, for example, a value (e.g., 5 watts) defined in advance in the WPC standard.

The TX also performs foreign object detection processing using the Q-value measurement method in response to a request from the RX. The TX receives an FOD Status Data packet from the RX. This packet includes the Reference Quality Factor Value and Reference Resonance Frequency Value described above.

Then, the TX performs foreign object detection using the Q-value measurement method. This foreign object detection is performed based on the following information:

The Quality Factor and resonant frequency of the transmitting antenna 105 measured by the TX before transmitting the DP.
A threshold based on the Reference Quality Factor Value and Reference Resonance Frequency Value received by the TX from the RX.
In the foreign object detection process using the Q-factor measurement method, in response to a request from the RX to the TX, the value of the Quality Factor of the transmitting antenna 105 measured by the TX before transmitting the DP is compared with the above threshold value, and the presence or absence of a foreign object and the possibility of its existence are determined based on the comparison result.

Next, in S1204, the TX and RX perform the Calibration phase processing (CAL processing) of the WPC standard. In the Calibration phase, the TX executes CAL processing of the Power Loss method based on the determined Reference Power value or GP value.

First, the RX transmits a signal to the TX that contains information about the received power in a light load state (hereinafter referred to as first reference received power information). A light load state is, for example, a load disconnection state, a load state in which the received power value of the RX is equal to or lower than a first threshold, or a load state in which the received power value of the RX is within a predetermined range (hereinafter referred to as the "first range").

In this embodiment, the first reference received power information is information indicating 500 milliwatts. The first reference received power information is information contained in the Received Power Data packet (mode 1) defined in the WPC standard, but other messages may also be used.

Hereinafter, the Received Power Data packet (mode 1) is denoted as RP1. The TX determines whether or not to accept the first reference received power information based on the Control Error Value contained in the Control Error (CE) data packet received from the RX.

If the TX accepts the first reference received power information, it sends an acknowledgment ACK to the RX. If the TX does not accept the first reference received power information, it sends a negative acknowledgment NAK to the RX.

Next, the RX performs processing to transmit to the TX a signal containing information about the received power in a load connection state (hereinafter referred to as second reference received power information). The load connection state is, for example, a maximum load state, a load state in which the transmitted power value is equal to or greater than a second threshold, or a load state in which the power received by the RX is maximum.

Here, "maximum power" refers to a power value close to the Reference Power. Alternatively, the load connection state is a load state in which the RX receiving power value is within a predetermined range (hereinafter referred to as the "second range"). Here, the second range is a range of power values higher than the first range.

In this embodiment, the second reference received power information is information indicating 15 watts. The second reference received power information is information contained in the Received Power Data packet (mode 2) defined in the WPC standard, but other messages may also be used.

Hereinafter, Received Power Data packet (mode 2) is referred to as RP2. TX determines whether or not to accept the second reference received power information based on the Control Error Value contained in the Control Error (CE) data packet received from RX.

If the TX accepts the second reference received power information, it sends an acknowledgment ACK to the RX. If the TX does not accept the second reference received power information, it sends a negative acknowledgment NAK to the RX. The TX sends an acknowledgment ACK to the second reference received power information from the RX, and completes the CAL process.

The above CAL process enables the TX to calculate the amount of power loss between the TX and the RX in the light load state and the load connected state based on the transmission power value of the TX and the received power value contained in the first and second reference received power information.

The TX can also calculate the amount of power loss between the TX and the RX for all possible transmission powers by performing an interpolation process between multiple power loss amounts. All possible transmission powers by the TX are, for example, any power within the range of the receiving power received by the RX in this embodiment, from 500 milliwatts to 15 watts.

Then, in S1205, the TX transmits power until the battery 207 of the RX is fully charged. In S1205, communication is performed in the Power Transfer phase of the WPC standard.

The RX repeatedly transmits a Control Error (CE) data packet (hereafter referred to as a "CE packet") to the TX at time intervals of t_interval. t_interval is a value defined by the WPC standard, and is, for example, 250 milliseconds.

The CE packet contains a request for how much to increase or decrease the transmission power. The TX adjusts the transmission power by controlling the current or voltage of the transmitting antenna 105 based on the received CE packet.

In other words, the CE packet contains parameter data for adjusting the transmission power. By repeating this process, transmission at the appropriate power according to the RX request is performed almost in real time.

When the battery 207 is fully charged, the RX sends an End Power Transfer data Packet (hereinafter referred to as the "EPT packet") to the TX to end the Power Transfer phase.

The RX can send an EPT packet for reasons other than full charge. Also, when the Power Transfer phase ends, the TX stops transmitting power to the RX for charging.

If the TX fails to receive the next CE packet after the time t_timeout has elapsed since the last CE packet was received, the TX determines that the RX has been removed from the charging station 300. In this case, the Power Transfer phase ends. t_timeout is a value defined by the WPC standard, and is, for example, 1500 milliseconds.

The RX may transmit packets other than CE packets to the TX during the Power Transfer phase. For example, there is a Charge Status Data Packet that notifies the TX of the status of the RX's battery 207.

This packet contains a Charge Status Value that indicates the percentage to which the battery 207 is charged. When the TX receives the Charge Status Data Packet, it notifies the user of the charging status, for example by displaying text or a diagram based on the Charge Status Value via the UI unit 110.

Regarding the Charge Status Data Packet, TX may be received at any time, and the user may be notified at any time.

In the Power Transfer phase, the TX transmits power to the RX and performs foreign object detection processing using the Power Loss method. For example, the amount of power loss between the TX and RX in the first detection state during the power transmission process is calculated from the difference between the transmitted power value and the received power value using CAL processing.

The calculated amount of power loss corresponds to the reference amount of power loss in the absence of a foreign object. If the TX determines that the difference between the amount of power loss between the TX and RX measured during power transmission after CAL processing and the reference amount of power loss is equal to or greater than a threshold value, it determines that the second detection state is present.

An example of the flow of processing related to power reception control executed by the RX will be described with reference to FIG. 8. This processing is realized, for example, by the control unit 201 of the RX executing a program read from the memory 208.

In S1301, the RX executes the processes defined as the Selection phase and Ping phase of the WPC standard, and waits for its own device to be placed on the TX. The RX detects that it has been placed on the TX, for example, by detecting a DP from the TX.

When the RX detects that its own device has been placed on the TX, in S1302 it transmits a signal including its own device's identification information to the TX using an ID Packet and a Configuration Data Packet.

The identification information of the RX may be transmitted by a method other than the I&C phase communication of the WPC standard. Also, other identification information such as BD_ADDR may be used as long as it is information that can identify each individual RX. Also, in S1302, the RX can transmit information other than the identification information to the TX.

Next, in S1303, the RX transmits a signal including information about the GP value requested by the TX, waits for a response from the TX, and then determines the GP. In S1303, communication takes place in the negotiation phase of the WPC standard.

The RX sends a FOD Status Data packet to the TX. This packet contains the Reference Quality Factor Value and the Reference Resonance Frequency Value.

Next, in S1304, the RX and TX perform the calibration phase process (CAL process) of the WPC standard. The process performed by the RX in this phase is as described above. After that, in S1305, the RX receives power until the battery 207 is fully charged.

In the Power Transfer phase, the RX and TX perform foreign object detection processing using the Power Loss method. In S1305, the RX repeatedly transmits a CE packet at intervals of t_interval, and finally transmits an EPT packet to the TX to end the processing.

As described above, the Power Loss method is a method for detecting foreign objects based on the results of measuring the amount of power loss while transmitting power from the TX to the RX. While this method has the disadvantage that the accuracy of foreign object detection decreases when the TX is transmitting a large amount of power, it has the advantage that high power transmission efficiency can be maintained because the foreign object detection process can be performed while continuing power transmission.

However, if foreign object detection is only performed using the Power Loss method during the Power Transfer phase, there is a possibility that a false positive will occur, or that a false positive will occur, resulting in a false positive determination that there is no foreign object even when there is actually a foreign object.

For example, consider the case where a foreign object is present near TX and RX during power transmission in the Power Transfer phase. In this case, there is a possibility that heat generation from the foreign object may increase, so there is a need to improve the accuracy of foreign object detection in the Power Transfer phase.

Here, we will explain a foreign object detection method using the waveform attenuation method. With this method, the TX can detect a foreign object based on the attenuation state of the transmission waveform (voltage waveform or current waveform) related to the power transmission performed by the RX. In other words, foreign object detection is possible without using a newly defined foreign object detection signal, etc.

FIG. 9 is a diagram explaining the principle of foreign object detection using the waveform attenuation method. It shows an example of foreign object detection using a transmission waveform related to power transmission from a power transmitting device 100 (TX) to a power receiving device 200 (RX). In FIG. 9, the horizontal axis represents time, and the vertical axis represents voltage or current values.

The waveform 600 shown in FIG. 9 shows, for example, the change over time in the voltage value of the high-frequency voltage applied to the TX power transmission antenna 105. Alternatively, it shows the change over time in the high-frequency voltage value or current value observed in a circuit including the TX power transmission antenna 105 and the resonant capacitor 107.

TX, which is transmitting power to RX via the power transmitting antenna 105, stops transmitting power at time _T0 . At time _T0 , the power supply for power transmission from the power supply unit 102 is stopped, and the power supply for power transmission to the power transmitting antenna 105 is stopped.

The frequency _f1 of the transmitting wave before the power transmission is stopped at time _T0 is a fixed frequency between 87 kHz and 205 kHz used in the WPC standard, for example. Point 601 on the waveform 600 is a point on the envelope of the high frequency voltage, and ( _T1 , _A1 ) indicates that the voltage value at time _T1 is _A1 .

Point 602 on waveform 600 is a point on the envelope of the high frequency voltage, and (T ₂ , A ₂ ) indicates that the voltage value at time T ₂ is A ₂ .

The Quality Factor (Q-factor, Q value) of the resonant circuit including the power transmitting antenna 105 and the resonant capacitor 107 can be obtained based on the change in voltage value over time after time _T0 .

For example, the TX calculates the Quality Factor using Equation 1 based on the time and voltage values at points 601 and 602 on the envelope of the high-frequency voltage, and _the frequency _f2 of the high-frequency voltage after power transmission is stopped at time T0.
Q = π f ₂ (T ₂ - T ₁ ) / ln (A ₁ / A ₂ ) (Equation 1)

In Equation 1, ln represents a natural logarithm function. Note that the frequency (f ₁ ) of the transmission wave when the TX is transmitting power to the RX may differ from the frequency (f ₂ ) of the transmission wave when the TX stops transmitting power to the RX.

The value of the Quality Factor decreases when a foreign object is present near TX and RX because the foreign object causes energy loss. Therefore, when looking at the slope of the attenuation of the voltage value, the slope of the line connecting points 601 and 602 is greater when a foreign object is present than when no foreign object is present.

If energy loss occurs due to a foreign object, the attenuation rate of the amplitude of waveform 600 increases. For example, in the waveform attenuation method, the presence or absence of a foreign object can be determined based on the attenuation state of the voltage value between points 601 and 602.

In order to actually determine whether or not there is a foreign object, it is possible to make a judgment by comparing some kind of numerical value that indicates the attenuation state. For example, when making a judgment using the Quality Factor, a value of the Quality Factor that is lower than the reference value means that the waveform attenuation rate (the degree of decrease in the amplitude of the waveform per unit time) is high.

As another example, there is a method of making the judgment using the slope of the line connecting points 601 and 602, which is calculated by ( _A1 - _A2 )/( _T2 - _T1 ).In addition, if the times ( _T1 and _T2 ) at which the attenuation state of the voltage values is measured are fixed, the presence or absence of a foreign object can be judged using the difference in the voltage values ( _A1 - _A2 ) or the ratio of the voltage values ( _A1 / _A2 ).

Alternatively, if the voltage value _A1 immediately after the power transmission is stopped is constant, the presence or absence of a foreign object can be determined using the voltage value _A2 after a predetermined time has elapsed. Alternatively, the presence or absence of a foreign object can be determined using the time ( _T2 - _T1 ) that has elapsed until the voltage value _A1 reaches the predetermined voltage value _A2 .

In the waveform attenuation method, it is possible to determine the presence or absence of a foreign object based on the attenuation state of the waveform during periods when power transmission is stopped. Indicators such as the Quality Factor that represent the attenuation state of the transmitted radio wave are collectively referred to as "waveform attenuation indicators" in this disclosure.

In addition, while the vertical axis in FIG. 9 has been described as the axis representing the voltage value of the high-frequency voltage applied to the TX power transmission antenna 105, the vertical axis in FIG. 9 may also represent the current value flowing through the power transmission antenna 105. As with the voltage value, the attenuation state of the current value during the power transmission stop period changes depending on the presence or absence of a foreign object.

When a foreign object is present, the waveform attenuation rate is higher than when no foreign object is present. Therefore, a foreign object can be detected by applying the same method described above to the time change in the current value flowing through the power transmitting antenna 105.

In other words, the Quality Factor calculated from the current waveform, the slope of the current value attenuation, the current value difference, the current value ratio, the current value absolute value, or the time it takes for the current value to reach a predetermined value can be used as waveform attenuation indicators to determine the presence or absence of a foreign object and detect the foreign object.

There is also a method based on both the attenuation state of the voltage value and the attenuation state of the current value. With this method, the presence or absence of a foreign object can be determined using an evaluation value calculated from the waveform attenuation index of the voltage value and the waveform attenuation index of the current value.

Note that the present invention is not limited to the example of measuring the waveform attenuation index during the period when the TX temporarily stops power transmission. The waveform attenuation index may be measured during the period when the TX temporarily reduces the power supplied from the power supply unit 102 from a predetermined power level to a lower power level.

In other words, the waveform attenuation index may be measured during a period in which the power transmitted to the power transmitting antenna 105 is temporarily reduced from a predetermined power level to a lower power level. In addition, the power transmitting unit 103 may limit the power transmission to the power transmitting antenna 105 (stopping power transmission or reducing the power transmission) as described above based on an instruction signal from the control unit 101.

In addition, in the above example, the voltage or current values are measured at two points in time during the period when the TX limits power transmission, but the voltage or current values may be measured at three or more points in time and used to calculate the waveform attenuation index.

With reference to FIG. 10, a foreign object detection method based on a transmission waveform using the waveform attenuation method will be described. The transmission waveform shown in FIG. 10 is a transmission waveform when detecting a foreign object using the waveform attenuation method, with the horizontal axis representing time and the vertical axis representing the voltage value or current value of the transmission antenna 105.

During the transient response period immediately after the TX starts transmitting power, the transmission waveform is not stable. Therefore, during this transient response period, the RX controls the TX so that it does not communicate (communication by amplitude modulation or load modulation).

The TX also controls the RX so that it does not communicate with the RX (communication using frequency shift keying). Hereinafter, this period is called the communication prohibition period. However, during the communication prohibition period, the TX transmits power to the RX.

After the communication prohibition period has elapsed, the TX transmits power to the RX. Hereinafter, this period will be referred to as the power transmission period. If the TX receives a request (packet, command) to execute a foreign object detection operation from the RX, the TX will temporarily suspend power transmission after a specified period has elapsed, or will temporarily reduce the transmission power.

Hereinafter, this predetermined period will be referred to as the preparation period. During the preparation period, the RX controls the TX so that it does not communicate using amplitude modulation or load modulation. In addition, the TX controls the RX so that it does not communicate using frequency shift keying.

By controlling so that no communication takes place during the preparation period, disturbance of the transmission wave is suppressed, and the TX can more accurately calculate the waveform attenuation index of the transmission wave, which will be described later. The request (packet, command) to execute the foreign object detection operation may be RP0, RP1, or RP2.

When the TX receives the execution request, the power transmission unit 103 suspends power transmission or temporarily reduces the transmission power, so that the amplitude of the transmitted wave attenuates. The period from the time when power transmission is suspended or the time when the transmission power is temporarily reduced to the time when power transmission is resumed or the return of the transmission power begins is called the transmission power control period.

Here, "resuming power transmission" means that the TX increases the transmission power to a predetermined value. Alternatively, the period from when the TX temporarily sets the value of the inverter input voltage input to the inverter in the power transmission unit 103 to 0 volts to when the TX increases the value of the inverter input voltage to a predetermined value is called the transmission power control period.

Alternatively, the period from when the TX temporarily reduces the inverter input voltage value to a predetermined first voltage value to when the TX increases the inverter input voltage value to a predetermined second voltage value is called the transmission power control period.

Alternatively, the period from when the TX temporarily sets the inverter output voltage value output by the inverter in the power transmission unit 103 to 0 volts to when the TX increases the inverter output voltage value to a predetermined voltage value is called the transmission power control period.

Alternatively, the period from when the TX temporarily reduces the inverter output voltage to a predetermined first voltage value to when the TX increases the inverter output voltage to a predetermined second voltage value is called the transmission power control period.

The control by the TX to temporarily stop power transmission or temporarily reduce the transmission power is called transmission power control. The control by the TX to temporarily set the input voltage or output voltage of the inverter in the power transmission unit 103 to 0 volts or temporarily reduce it to a specified value is called transmission power control.

The TX calculates a waveform attenuation index based on the attenuated waveform, and compares the calculated waveform attenuation index with a threshold value to determine whether or not a foreign object is present, or the possibility that a foreign object is present (probability of presence) (hereinafter also referred to as foreign object determination).

During the transmission power control period, the RX controls the TX so that it does not communicate using amplitude modulation or load modulation. Also, the TX controls the RX so that it does not communicate using frequency shift keying.

By controlling so that communication does not take place during the transmission power control period, disturbance of the transmission wave is suppressed, and the TX can calculate the waveform attenuation index of the transmission wave with higher accuracy. In addition, foreign object detection can be performed during the transmission power control period, communication prohibition period, or power transmission period.

If no foreign object is detected after the transmission power control period has elapsed, the TX will resume transmission or control the return of transmission power. During the transient response period immediately after this control begins, the transmission waveform is not stable, so this period becomes a communication prohibited period. After this, the TX transitions to a transmission period in which stable power transmission is performed from the TX to the RX.

As described above, the TX repeatedly controls the start of power transmission, communication prohibited period, power transmission period, preparation period, and transmission power control period. The TX calculates a waveform attenuation index based on the attenuated waveform at a specified timing, and performs a foreign object determination based on the result of comparing the calculated waveform attenuation index with a threshold value.

In other words, foreign object determination can be performed based on voltage or current values at two or more points in time during a specified period when power transmission is restricted (including the suspension of power transmission). Also, during the preparation period, power transmission control period, and communication prohibited period, the RX controls the TX so that it does not communicate using amplitude modulation or load modulation.

The TX also controls the RX so that it does not communicate with the RX using frequency shift keying. In other words, the TX controls the RX so that it does not communicate with the RX for a predetermined period (first period) after receiving an execution request (packet, command) from the RX.

The WPC standard specifies the period during which the TX cannot transmit packets to the RX (packet transmission is prohibited) after the TX receives a packet other than an execution request from the RX during the Power Transfer phase.

The first period is longer than the above period. In addition, the RX controls not to communicate with the TX for a predetermined period (second period) after sending an execution request (packet, command) to the TX.

The WPC standard specifies a period during which the RX cannot transmit packets to the TX (packet transmission is prohibited) after the RX transmits a packet other than an execution request to the TX during the Power Transfer phase. The second period is a period longer than the period.

However, during the transmission power control period, if elements such as the power receiving unit 203, the charging unit 206, and the battery 207 are connected to the power receiving antenna 205 and the resonant capacitor 211 of the power receiving device 200, the waveform attenuation index is affected by the load caused by these elements.

In other words, the value of the waveform attenuation index changes depending on the state of the power receiving unit 203, the charging unit 206, and the battery 207. As a result, even if the value of the waveform attenuation index is large, for example, it becomes difficult to distinguish whether this is due to the influence of a foreign object or a change in the state of the power receiving unit 203, the charging unit 206, the battery 207, etc.

Therefore, when measuring the waveform attenuation index to detect foreign objects, the control unit 201 of the RX turns off the first switch unit 209 during the preparation period. The RX sends an execution request (packet, command) to the TX, and executes the above processing during the preparation period.

Alternatively, the RX executes the above process at the same time as it transmits an execution request packet (command) to the TX. This makes it possible to suppress the influence of the battery 207.

Also, instead of disconnecting the first switch unit 209, the same effect can be obtained by setting it to a light load state.Also, instead of disconnecting the first switch unit 209, the same effect can be obtained by performing load control so that the power received by the RX is minimized.

Alternatively, instead of turning off the first switch unit 209, the same effect can be achieved by controlling the load so that the power received by the RX is within a predetermined range or is below a threshold.

Here, in "power within a predetermined range" or "power below a threshold value," "power" refers to power with a value of approximately 10% of the Reference Power. Alternatively, instead of the first switch unit 209 being disconnected, the RX may control the load so that a predetermined power is supplied to the load.

These can be achieved by controlling the first switch unit 209. The operations in the light load state include the above operations. The RX maintains the above control even during the transmission power control period.

Then, after the power transmission is resumed, the RX releases the above-mentioned control and controls to return to the original state. Alternatively, the control unit 201 turns on the second switch unit 210 to short it, and causes a current to flow through the closed loop formed by the power receiving antenna 205, the resonant capacitor 211, and the second switch unit 210.

This makes it possible to suppress the effects of the power receiving unit 203, the charging unit 206, and the battery 207. The RX transmits a request (packet, command) to the TX to perform foreign object detection, and the above process is carried out during the preparation period.

Alternatively, the RX executes the above process at the same time as sending an execution request (packet, command) to the TX. The RX maintains the above control even during the transmission power control period. Then, after the power transmission is resumed, the RX releases the above control and performs control to return to the original state.

By obtaining a waveform attenuation index based on the power transmission waveform measured with the first switch unit 209 disconnected or with the second switch unit 210 turned on and shorted (connected), more accurate foreign object detection is possible. Alternatively, by both disconnecting the first switch unit 209 and shorting (connecting) the second switch unit 210, even more accurate foreign object detection is possible.

Alternatively, during the preparation period, RX may switch to a low power consumption mode or control so that power consumption is constant, with the first switch unit 209 turned ON to short circuit and the second switch unit 210 turned OFF to disconnect.

RX sends an execution request (packet, command) to TX and executes the above process during the preparation period. Alternatively, RX executes the above process at the same time as sending an execution request (packet, command) to TX.

The RX maintains the above-mentioned control even during the transmission power control period. Then, after power transmission is resumed, the RX releases the above-mentioned control and performs control to return to the original state. If the power consumption in the RX is not constant or if a large amount of power is consumed, the value of the waveform attenuation index based on the attenuated waveform will be affected by fluctuations in power consumption.

In order to mitigate this effect, it is effective to limit or stop the operation of software applications running on the RX, or to set the hardware function blocks of the RX to a low power consumption mode or a stopped mode.

More accurate foreign object detection is possible by detecting foreign objects using a waveform attenuation index based on the transmission waveform measured with RX power consumption suppressed.

Similarly, in the case of TX, if elements such as the power transmission unit 103, the first communication unit 104, and the power supply unit 102 are connected to the power transmission antenna 105 and the resonant capacitor 107 of the power transmission device 100 when the waveform attenuation index is measured, the waveform attenuation rate is affected by these elements.

In other words, the value of the waveform attenuation index changes depending on the state of the power transmission unit 103, the first communication unit 104, and the power supply unit 102. As a result, even if the value of the waveform attenuation index is large, for example, it becomes difficult to distinguish whether this is due to the influence of a foreign object or the influence of the power transmission unit 103, the first communication unit 104, and the power supply unit 102.

When the TX receives a request (packet, command) from the RX to execute a foreign object detection operation, the control unit 101 turns on the switch unit 108 during the preparation period. In other words, the control unit 101 makes the state in which a current flows through the closed loop circuit formed by the power transmitting antenna 105, the resonant capacitor 107, and the switch unit 108.

This makes it possible to suppress the influence of the power transmission unit 103, the first communication unit 104, and the power supply unit 102 when measuring the waveform attenuation index in TX. Alternatively, by providing a switch (not shown) between the power transmission antenna 105 and the power transmission unit 103 and turning off the switch during the preparation period, it becomes possible to suppress the influence of the power supply unit 102, the power transmission unit 103, and the first communication unit 104.

The TX maintains the above-mentioned control even during the transmission power control period. Then, after the power transmission is resumed, the TX releases the above-mentioned control and controls to return to the original state. Alternatively, a switch may be provided between the power transmitting unit 103 and the closed loop circuit formed by the power transmitting antenna 105, resonant capacitor 107, and switch unit 108.

When the TX measures the waveform attenuation index and detects a foreign object, it can control the switch to disconnect the closed loop circuit from the power transmission unit, thereby suppressing the above effects.

As described above, at least one of the following states is realized: a short circuit (connection) state with the switch unit 108 turned ON; a disconnection state between the power transmitting antenna 105 and the power transmitting unit 103 by a switch; and a disconnection state between the closed loop circuit and the power transmitting unit 103 by a switch. This allows for more accurate foreign object detection.

Next, we will explain how to set a threshold value for the waveform attenuation index in order to detect the status of TX and RX and to determine whether a foreign object is present based on the waveform attenuation method. By comparing the measured value of the waveform attenuation index with the threshold value, it is possible to determine whether a foreign object is present based on the comparison result.

The first threshold setting method is a method in which the TX holds a predetermined threshold value, which is a common value that does not depend on the RX to which power is transmitted. This threshold value is a fixed value, or a variable value that the TX determines depending on the situation.

If a foreign object is present, the waveform attenuation rate of the transmission waveform during the transmission power control period will be high. Therefore, the value of the waveform attenuation index obtained when no foreign object is present is stored in advance, and this value is set as the threshold value.

By comparing the measured value of the waveform attenuation index with a threshold value, it can be determined that "foreign matter is present" or "there is a high possibility that a foreign matter is present." For example, if Quality Factor is used as the waveform attenuation index, the TX compares the measured value of Quality Factor with a predetermined threshold value.

The threshold value is set based on the measurement value in the first detection state or a value that takes into account the measurement error. If the measurement value of the Quality Factor is smaller than the threshold value, it is determined that "foreign matter is present" or "there is a high possibility that a foreign matter is present."

If the measured value of the Quality Factor is above the threshold, it is determined that there is no foreign matter or that there is a low possibility of the presence of a foreign matter.

The second threshold setting method is a method in which the TX adjusts and determines the threshold based on information transmitted from the RX. A notable difference from the first threshold setting method is that the value of the waveform attenuation index may differ depending on the RX that is the target of power transmission and is placed on the TX.

The reason is that the electrical characteristics of the RX, which is electromagnetically coupled via the TX's transmitting antenna, affect the value of the waveform attenuation index. For example, if Quality Factor is used as the waveform attenuation index, the Quality Factor measured by the TX when no foreign object is present may differ depending on the RX placed on the TX.

The RX therefore retains Quality Factor information for each TX when the RX is placed on the TX in the absence of any foreign object, and notifies the TX of the Quality Factor information. The TX adjusts and determines the threshold for each RX based on the Quality Factor information received from the RX.

More specifically, in the Negotiation phase, the TX receives a FOD Status Data Packet containing information on the Reference Quality Factor Value, and adjusts and determines the threshold value in the Q-value measurement method.

The TX uses this Reference Quality Factor Value to determine the threshold value, regarding it as equivalent to "Q value information when the RX is placed on the TX in the absence of any foreign object." In other words, the TX can adjust and determine the threshold value for foreign object detection using the waveform attenuation method based on the Reference Quality Factor Value.

The Reference Quality Factor Value sent from the RX to the TX during the Negotiation phase is information used for foreign object detection in the Q-value measurement method, which originally measures the Quality Factor in the frequency domain.

However, when the Quality Factor value is used as the waveform decay index, although the method of deriving the Quality Factor is different, the Quality Factor can also be calculated from the waveform in Figure 9, for example, using the above formula 1, using the waveform decay method that measures the Quality Factor in the time domain.

Therefore, it is possible to set the Q value threshold of the waveform attenuation method based on the Reference Quality Factor Value. Note that the value of the waveform attenuation index, which takes into account a specified value (a value corresponding to the measurement error) for the Reference Quality Factor Value, may be set as the threshold for foreign object determination.

In this way, the TX sets the threshold value for the Quality Factor of the waveform attenuation method based on the information already sent from the RX to the TX in the Negotiation phase, eliminating the need to perform new measurements or other processing to set the threshold value. As a result, it becomes possible to set the threshold value in a shorter time. Foreign object determination based on the set threshold value and the measured value of the Quality Factor is as described above.

The third threshold setting method is a method in which the TX measures the waveform attenuation index when no foreign object is present, and adjusts and determines the threshold based on the information from the measurement result. Below, the timing for pre-measuring the waveform attenuation rate when no foreign object is present is explained.

In the Negotiation phase of the WPC standard, if foreign object detection using the Q-value measurement method results in a determination that no foreign object is present, the system proceeds to the Calibration phase and the Power Transfer phase. In other words, when the phase progresses beyond the Negotiation phase, it means that the result of foreign object detection using the Q-value measurement method indicates that no foreign object is present.

There is a high possibility that the waveform attenuation index can be measured in the absence of a foreign object during either the Negotiation phase, the Calibration phase, or the Power Transfer phase. Therefore, the timing for measuring the waveform attenuation index in the absence of a foreign object may be either the Negotiation phase, the Calibration phase, or the Power Transfer phase.

For example, assume that the waveform attenuation index is measured during the power transfer phase. The timing for measuring the waveform attenuation index in the absence of a foreign object is set to the first stage of the power transfer phase.

The reason for this is that the more time that passes from the point at which the Q-value measurement method determines that there is no foreign object, the higher the probability that a foreign object will be present in the vicinity of the TX and RX. The timing is specified by the RX or TX, and the TX measures the waveform attenuation index at that time and sets the value of that waveform attenuation index as the threshold value.

If the timing is specified by the RX (or TX), the RX (or TX) notifies the TX (or RX) of the timing by sending a specified packet to the TX (or RX). Note that a value obtained by adding a specified value (a value corresponding to the measurement error) to the waveform attenuation index may be set as the threshold for foreign object determination.

The fourth threshold setting method is a method in which the TX adjusts and determines the threshold depending on the transmission power. The value of the waveform attenuation index may differ depending on the transmission power of the TX. This is because the amount of heat generated and the characteristics of the TX's electrical circuitry change depending on the transmission power of the TX, which affects the value of the waveform attenuation index.

The TX measures the waveform attenuation index for each transmission power and adjusts and determines the threshold based on the measurement results, enabling more accurate foreign object detection.

FIG. 11 is a diagram for explaining a method for setting a threshold value for foreign object determination for each TX transmission power in the waveform attenuation method. In FIG. 11, the horizontal axis represents the transmission power of the power transmitting device 100, and the vertical axis represents the waveform attenuation index (waveform attenuation rate) of the voltage waveform or current waveform.

On the graph line indicated by the straight line segment 1102, point 1100 corresponds to the transmission power value Pt1 and the waveform attenuation index δ1, and point 1101 corresponds to the transmission power value Pt2 and the waveform attenuation index δ2. On the graph line, point 1103 corresponds to the transmission power value Pt3 and the waveform attenuation index δ3.

First, the RX controls the load so that the RX is in a light load state when power is transmitted from the TX. In a light load state, no power is supplied to the load of the RX, only power below a threshold is supplied, or power within a predetermined range (hereinafter referred to as the "third range") is supplied.

The transmission power value of the TX in this state is Pt1. Then, the RX transmits a packet to the TX requesting that the TX perform measurement of the waveform attenuation index. Then, when the TX receives this packet, it stops transmission while the RX load is controlled to a light load state, or reduces the transmission power, and measures the waveform attenuation index δ1.

At this time, the TX recognizes the transmission power value Pt1 and stores in memory CP1100, which is a calibration point that associates the transmission power value Pt1 with the waveform attenuation index δ1.

Next, the RX controls the load connection state. The load connection state is a state in which, when power is transmitted from the TX, maximum power is supplied to the load of the RX, or power equal to or greater than a threshold is supplied, or power within a specified range (hereinafter referred to as the "fourth range") is supplied.

Here, the "fourth range" is a power range greater than the "third range." The transmission power value of the TX in this state is Pt2. Then, the RX transmits a packet to the TX requesting that it perform a measurement of the waveform attenuation index.

When the TX receives the packet, it stops transmission or reduces the transmission power while the RX load is controlled to a load-connected state, and measures the waveform attenuation index δ2.

At this time, the TX stores in memory CP1101, which associates the transmission power value Pt2 with the waveform attenuation index δ2. Next, the TX performs linear interpolation between CP1100 and CP1101 to generate line segment 1102.

Line segment 1102 shows the relationship between the transmission power and the waveform attenuation index of the waveform observed by the transmission antenna 105 in the first detection state in which no foreign object is present around the TX and RX. Therefore, based on line segment 1102, the TX can estimate the waveform attenuation index of the waveform observed by the transmission antenna 105 for each transmission power value in the first detection state.

For example, in the case of a transmission power value Pt3, the waveform attenuation index is estimated to be δ3 from point 1103 on line segment 1102 corresponding to Pt3. Based on the estimation result, the TX can calculate a threshold value used to determine the presence or absence of a foreign object for each transmission power value.

For example, a waveform attenuation index that is larger than the estimated result of the waveform attenuation index in the first detection state at a certain transmission power value by a predetermined value (a value corresponding to the measurement error) can be set as the threshold value for determining foreign objects.

The CAL processing performed by the power transmitting device 100 and the power receiving device 200 in order for the power transmitting device 100 to obtain a combination of the transmitted power value and the waveform attenuation index is hereinafter referred to as "CAL processing of the waveform attenuation method."

Furthermore, the power transmitting device 100 and the power receiving device 200 can execute the CAL process of the waveform decay method multiple times. CAL process of the waveform decay method that is executed again after executing the CAL process of the waveform decay method once is referred to below as "recalibration process of the waveform decay method."

The recalibration process is abbreviated as RECAL process. In the above example, measurements were taken at two points, the transmission power values Pt1 and Pt2, but to improve accuracy, measurements may be taken at three or more points to calculate the waveform attenuation index for each transmission power.

The RX may perform the light load state control and the load connection state control after notifying the TX by a specified packet that the control will be performed. Also, either of the two controls may be performed first.

The calculation process of the threshold value used to determine the presence of a foreign object for each load (or each transmission power value) described in this embodiment may be performed in the calibration phase. As described above, in the calibration phase, the TX acquires data required for foreign object detection using the Power Loss method.

At that time, the TX acquires data on the received power value and power loss of each RX when the load state of the RX is a light load state and when the load state is connected. Therefore, the measurements of CP1100 and CP1101 in FIG. 11 may be performed together with the measurement of power loss when the RX is in a light load state and when the RX is in a loaded state during the calibration phase.

For example, when the TX receives a signal having first reference received power information from the RX, in addition to the predetermined processing to be performed in the calibration phase, the TX measures CP1100. This first reference received power information is the RP1 information defined in the WPC standard, but other messages may also be used.

When the TX receives a signal having second reference received power information from the RX, the TX measures CP1101 in addition to the predetermined processing to be performed in the calibration phase. This second reference received power information is the RP2 information defined in the WPC standard, but other messages may be used.

There is no longer a need to set aside separate periods for measuring CP1100 and CP1101, so measurements of CP1100 and CP1101 can be performed in a shorter time.

In this way, based on the information of the waveform attenuation index measured by the TX at each transmission power, the TX adjusts and sets the threshold value of the waveform attenuation index for each transmission power. For example, when using Quality Factor as the waveform attenuation index, the TX compares the measured value of Quality Factor with the threshold value determined by the above method.

If the measured Q value is smaller than the threshold, it is determined that "foreign object is present" or "there is a possibility that a foreign object is present." If the measured Quality Factor value is equal to or greater than the threshold, it is determined that "no foreign object is present" or "there is a low possibility that a foreign object is present." In this way, threshold values are set for each TX transmission power, enabling more accurate foreign object determination.

The threshold value for determining whether or not a foreign object is detected is not limited to one, and multiple threshold values can be set in stages. For example, the first threshold value is set as a threshold value for determining whether "there is an abnormal condition", the second threshold value is set as a threshold value for determining whether "there is a high possibility of an abnormal condition", the third threshold value is set as a threshold value for determining whether "there is a low possibility of an abnormal condition", and the fourth threshold value is set as a threshold value for determining whether "there is no abnormal condition".

In addition, there is a possibility that accuracy cannot be expected by performing the foreign object detection process only once. For example, when performing foreign object detection using the waveform attenuation method, if one transmission power control is performed and a foreign object is determined from the waveform attenuation index at that time, there is a possibility that disturbances will occur in the amplitude and phase of the transmitted wave during the transmission power control period.

Noise may be introduced during the transmission power control period, or the RX may be misaligned when placed on the TX. In this case, if the value of the waveform attenuation index calculated from the transmission waveform during one transmission power control period is not accurate, it may lead to an erroneous foreign object determination.

The TX then performs multiple transmission power controls, measures the waveform attenuation index from the transmission waveform during multiple transmission power control periods, and is able to perform more accurate foreign object determination based on the results of multiple measurements.

Next, a first measurement method will be described as a method for measuring an indicator of the coupling state between the transmitting antenna and the receiving antenna. The measurement performed in the first measurement method will be referred to as the first measurement below. In wireless power transmission, power is transmitted by electromagnetically coupling the transmitting antenna 105 and the receiving antenna 205.

By passing an alternating current through the transmitting antenna 105 and changing the magnetic flux that penetrates the receiving antenna 205, a voltage is induced in the receiving antenna 205. The coupling coefficient (denoted as k, and its value is called the k value), which is an index that represents the coupling state between the transmitting antenna and the receiving antenna, is, for example, "k = 1" when all (100%) of the magnetic flux generated by the transmitting antenna penetrates the receiving antenna.

When 70% of the magnetic flux generated by the transmitting antenna penetrates the receiving antenna, k = 0.7. In this case, the remaining magnetic flux (30%) generated by the transmitting antenna becomes leakage magnetic flux.

This is the magnetic flux generated by the transmitting antenna that did not penetrate the receiving antenna. Therefore, when the coupling between the transmitting antenna and the receiving antenna is good and the k value is large, the transmission efficiency of power transmitted from TX to RX is high. Conversely, when the coupling is not good and the k value is small, the transmission efficiency of power transmitted from TX to RX is low.

The k value can decrease if a foreign object (such as a metal piece) gets between the transmitting antenna and the receiving antenna, or if the transmitting antenna and the receiving antenna are misaligned. Or the distance between the transmitting antenna and the receiving antenna becomes too large.

If a foreign object gets between the transmitting antenna and the receiving antenna, heat may be generated in the object. Also, if the transmitting antenna and the receiving antenna are misaligned or separated, there will be a lot of leakage magnetic flux, which may cause a large amount of noise in the surrounding area.

When the k value is small, appropriate control is required to achieve safer and higher quality wireless power transmission. In this embodiment, a detection process is performed for the coupling state index (including the coupling coefficient) between the transmitting antenna and the receiving antenna to improve the detection accuracy of foreign objects and the detection accuracy when the positional deviation or distance is large.

With reference to Figure 12, a method for measuring the coupling state indicator of the power transmitting antenna and the power receiving antenna will be described. Figure 12 (A) is an equivalent circuit diagram for explaining the first measurement method. The definitions of various quantities related to the power transmitting antenna (power transmitting coil) on the primary side (TX) are shown below.

r1: Winding resistance of the transmitting antenna.
L1: Self-inductance of the transmitting antenna.
V1: The transmitting voltage (input voltage) across the transmitting antenna, measured by the TX.

The following are definitions of various quantities related to the receiving antenna (receiving coil) on the secondary side (RX).
r2: Winding resistance of the receiving antenna.
L2: Self-inductance of the receiving antenna.
V2: The receiving voltage (output voltage) across the receiving antenna measured by the RX.

The coupling coefficient (k) between the power transmitting antenna and the power receiving antenna can be calculated by the following formula 2.
k = (V2/V1) · √(L1/L2) (Equation 2)

When the TX calculates the coupling coefficient k, the RX notifies the TX of the measured receiving voltage V2 and the value of the self-inductance L2 of the receiving antenna that the RX holds in advance. The TX calculates the k value using the measured transmitting voltage V1, the value of the self-inductance L1 of the transmitting antenna that the TX holds in advance, and the receiving voltage V2 and self-inductance L2 values received from the RX.

Alternatively, RX can notify TX of a constant calculated using either or both of L1 and L2, and V2, and TX can calculate the k value using the constant and V2 received from RX, and the transmission voltage V1 measured by TX.

On the other hand, when the RX calculates the coupling coefficient k, the TX notifies the RX of the measured transmission voltage V1 and the previously stored value of the self-inductance L1 of the transmission antenna. The RX calculates the k value using the measured receiving voltage V2, the previously stored value of the self-inductance L2 of the receiving antenna, and the values of the transmission voltage V1 and self-inductance L1 received from the TX.

Alternatively, the TX can notify the RX of a constant calculated using either or both of L1 and L2, and V1, and the RX can calculate the k value using the constant and V1 received from the TX, and the receiving voltage V2 measured by the RX.

The transmission voltage V1 is calculated by the TX actually measuring the voltage applied to the transmission antenna, or by the TX calculating it from the set value of the transmission power. Alternatively, the transmission voltage V1 may be set as the set value of the transmission voltage during transmission.

In addition, the transmission voltage V1 applied to the transmission antenna can be calculated from the transmission voltage (denoted as V3) applied to a circuit (e.g., an inverter) in the TX transmission unit 103 and the voltage across the resonant capacitor 107.

Here, the transmission voltage V3 is, for example, the inverter input voltage input to the inverter of the power transmission unit 103 of the TX, or the inverter output voltage output by the inverter. In this case, the TX may also calculate the transmission voltage V3 from the set value of the transmission power.

Alternatively, the TX may actually measure the transmission voltage V3 and the voltage across the resonant capacitor 107, and use these to determine the transmission voltage V1. Alternatively, the TX may transmit the measured values of the transmission voltage V3 and the voltage across the resonant capacitor 107 to the RX, and the RX may determine the transmission voltage V1, thereby calculating the k value.

Also, when the TX or RX performs the first measurement, the RX may control the third switch unit 213 to be turned OFF so that the terminal of the power receiving antenna 205 is in an open state. This makes it possible to open both ends of the power receiving antenna as shown in FIG. 12(A).

The first measurement is not affected by the resonant capacitor 211, the power receiving unit 203, the charging unit 206, or the battery 207, so the coupling coefficient k can be measured with higher accuracy. In addition, the power receiving voltage V2 applied to the power receiving antenna can be calculated from the power receiving voltage (denoted as V4) applied to the circuit of the RX power receiving unit 203 and the voltage across the resonant capacitor 211.

Here, the receiving voltage V4 is, for example, the rectifier input voltage input to the rectifier of the RX receiving unit 203. Alternatively, the receiving voltage V2 applied to the receiving antenna can be calculated from the receiving voltage (denoted as V5) applied to the circuit of the RX receiving unit 203 and the voltage across the resonant capacitor 211.

Here, the receiving voltage V5 is, for example, the rectifier output voltage output from the rectifier of the receiving unit 203 of the RX. In this case, the RX may actually measure the receiving voltage V4 and the voltage across the resonant capacitor 211, and use these to determine the receiving voltage V2.

Alternatively, RX may actually measure the receiving voltage V5 and the voltage across the resonant capacitor 211, and use these to determine the receiving voltage V2. Alternatively, RX may transmit the measured values of the receiving voltage V4 and the voltage across the resonant capacitor 211 to TX, and TX may determine the receiving voltage V2, thereby calculating the k value.

Alternatively, the RX may transmit the measured power receiving voltage V5 and the voltage across the resonant capacitor 211 to the TX, and the TX may calculate the power receiving voltage V2 to calculate the k value.

Alternatively, when the TX or RX performs the first measurement, the RX may be controlled to be in a light load state or a load-connected state. By keeping the load state of the RX constant, it becomes possible to measure the coupling coefficient k with higher accuracy.

Alternatively, the TX or RX may be controlled to perform the first measurement in both a lightly loaded state and a loaded state of the RX. Alternatively, the TX or RX may be controlled to perform the first measurement in each of three or more loaded states of the RX. The coupling states in the loaded states of multiple RXs can be measured, and based on the results, the coupling state can be determined with higher accuracy.

In addition to the coupling coefficient, there are several other quantities that can be used as indicators of the electromagnetic coupling state between the transmitting antenna and the receiving antenna, and in this disclosure, these are collectively referred to as "coupling state indicators." Each coupling state indicator has a value that corresponds to the electromagnetic coupling state between the transmitting antenna and the receiving antenna.

The contents of this embodiment can also be applied when using other coupling state indices other than the coupling coefficient.

For example, there is a method of using the transmission voltage V3 applied to a circuit (e.g., an inverter) of the power transmitting unit 103 of the TX and the receiving voltage V4 applied to a circuit (e.g., a rectifier) of the power receiving unit 203 of the RX as the coupling state indicator.

These voltage values can be used to calculate the coupling state index between the transmitting antenna and the receiving antenna. Alternatively, the coupling state index between the transmitting antenna and the receiving antenna can be calculated using the transmitting voltage V3 applied to a circuit (e.g., an inverter) in the transmitting unit 103 of the TX and the voltage V5 applied to a circuit (e.g., a rectifier) in the receiving unit 203 of the RX.

Here, voltage V5 is, for example, the rectifier output voltage output from the rectifier in the power receiving unit 203 of RX, or the voltage applied to a load (charging unit, battery). TX notifies RX of the transmission voltage V3, and RX can calculate the coupling state index using the notified V3 and V4 or V5.

At this time, the TX notifies the RX of a constant calculated using the electrical characteristics of the transmitting antenna (e.g., L1), and the RX can use this constant to calculate the coupling state index.

Alternatively, RX notifies TX of the receiving voltage V4 or V5, and TX calculates the value of the coupling state index using the notified V4 or V5 and V3. At this time, RX notifies TX of a constant calculated using the electrical characteristics of the receiving antenna (e.g. L2), and TX can calculate the coupling state index using that constant.

TX and RX exchange information on the values of voltages V1 to V5, the values of self-inductances L1 and L2, and constants that represent the electrical characteristics of the transmitting and receiving antennas. The following explains the timing of measuring the voltage values and the timing of sending and receiving each piece of information.

The measurement of each voltage value is performed, for example, during the Ping phase. During the Ping phase, the TX transmits a DP to the RX. Therefore, any of the voltage values V1, V2, V3, V4, and V5 that are generated when the DP is transmitted can be used.

In the Ping phase, the TX and RX measure one of the values V1 to V5 and store it in memory 106 or memory 208.

The TX transmits a predetermined transmission request packet to the RX to request the transmission of a packet containing information on any or all of the voltage values V2, V4, and V5. When the RX receives the transmission request packet, it transmits to the TX a predetermined packet containing information on any or all of the voltage values V2, V4, and V5.

The TX receives a predetermined packet containing information on any or all of the voltage values V2, V4, and V5 notified from the RX, and stores the information in memory 106. The information contained in the predetermined packet may include not only the receiving voltage of the RX, but also the receiving power, the requested receiving power value, the value of the self-inductance L2, a constant calculated using the electrical characteristics of the receiving antenna, and other information.

Information regarding the temperature of the RX may also be included. The TX receives a signal including this information from the RX, and can use this information and the coupling status indicator to perform more appropriate control. As the specified packet, the Signal Strength Data packet can be used to notify the TX of the RX information.

Alternatively, the specified packet may be an Identification Data packet or an Extended Identification Data packet in the I&C phase.

Or it may be a Configuration Data packet. Or it may be a packet in the Calibration phase or the Power Transfer phase.

In other words, it may be RP1, RP2, or RP0. Note that this is not limited to the example where the voltage value generated when the TX transmits the DP is used. Any of the voltage values V1 to V5 generated when the TX transmits the AP in the Selection phase may be used.

Alternatively, any of the voltage values V1 to V5 that are generated when TX transmits power to RX during the Power Transfer phase may be used.

The RX transmits a specified transmission request packet to the TX to request the transmission of a packet containing information on either V1 or V3, or all of the voltage values. When the TX receives the transmission request packet, it transmits to the RX a specified packet containing information on either V1 or V3, or all of the voltage values.

The RX receives a predetermined packet containing information on either or all of the voltage values V1 and V3 notified from the TX, and stores the information in memory 208. The information contained in the predetermined packet may include not only the TX voltage, but also the transmission power value, the transmittable power value, the value of self-inductance L1, a constant calculated using the electrical characteristics of the transmission antenna, and other information.

Alternatively, it may include the results of foreign object detection using a foreign object detection method (power loss method, Q-value measurement method, waveform attenuation method), or information regarding the TX temperature and the current value of the transmitting antenna 105.

The RX receives the information from the TX and can use the information and the coupling status indicator to perform more appropriate control. In addition, the TX can notify the RX of the information by using a Power Transmitter Capabilities (CAP) Data Packet as a specified packet.

Alternatively, the TX can communicate information to the RX using a Power Transmitter Identification (ID) data packet.

Note that this is not limited to the example where the voltage value generated when the TX transmits the DP is used. Any of the voltage values V1 to V5 generated when the TX transmits the AP in the Selection phase may be used. Alternatively, any of the voltage values V1 to V5 generated when the TX transmits power to the RX in the Power Transfer phase may be used.

When performing the first measurement, the RX may control the third switch section 213 between the resonant capacitor 211 and the power receiving section 203 to be turned OFF, so that the terminal of the circuit formed by the power receiving antenna 205 and the resonant capacitor 211 is in an open state.

As a result, the first measurement is not affected by the power receiving unit 203, the charging unit 206, and the battery 207, making it possible to measure the coupling state index with higher accuracy. Alternatively, when performing the first measurement method, the RX may control the load so that the above-mentioned light load state is achieved.

When implementing the first measurement method, the RX may control the load so that the load is in the load connection state described above. This makes it possible to measure the coupling state index while maintaining the load state in a specified state, enabling more accurate state detection.

Next, a second measurement method will be described as another example of a method for measuring the coupling state indicator between a transmitting antenna and a receiving antenna. The measurement performed in the second measurement method will be referred to as the second measurement below. Figure 12 (B) is an equivalent circuit diagram for explaining the second measurement method.

r1, r2, L1, and L2 are the same as in Figure 12(A). The definitions of the quantities related to the transmitting antenna (coil) on the primary side (TX) are shown below.

V6: Input voltage (transmission voltage) of the transmission antenna when the receiving antenna side is shorted.
V7: Input voltage (transmission voltage) of the transmission antenna when the receiving antenna side is in an open state.
I1: The current flowing through the transmitting antenna when the receiving antenna is shorted.
I2: The current flowing through the transmitting antenna when the receiving antenna is in an open state.

The coupling coefficient k can be calculated by the following formula 3.
k = √(1-Lsc/Lopen) (Equation 3)

Lsc in Equation 3 represents the inductance of the power transmitting antenna when both ends of the power receiving antenna are short-circuited. For example, the control unit 201 sets the third switch unit 213 and the second switch unit 210 to the ON state (short-circuit state).

In this state, the inductance value of the power transmitting antenna is measured to obtain the Lsc value. The inductance value of the power transmitting antenna can be calculated from the input voltage V6 and current I1 of the power transmitting antenna.
In Equation 3, Lopen represents the inductance of the power transmitting antenna when both ends of the power receiving antenna are open. For example, the control unit 201 sets the third switch unit 213 to the OFF state (open state). In this state, the Lopen value can be obtained by measuring the inductance value of the power transmitting antenna.

The inductance value of the transmitting antenna can be determined from the input voltage V7 and current I2 of the transmitting antenna. In the second measurement method, the coupling state index (coupling coefficient) can be determined from the input voltage and current of the transmitting antenna when both ends of the receiving antenna are short-circuited and open.

TX can also calculate the coupling state index based on the transmission voltage and current applied to a circuit (e.g., an inverter) included in the power transmission unit 103. In this case, the input voltages V6 and V7 represent the transmission voltage applied to a circuit (e.g., an inverter) included in the power transmission unit 103.

Here, the transmission voltages V6 and V7 applied to the circuit included in the power transmission unit 103 of the TX are, for example, the inverter input voltage or the inverter output voltage. The input voltages V6 and V7 may also be the voltages applied to both terminals of a series resonant circuit consisting of a power transmission antenna and a resonant capacitor.

Alternatively, the transmission voltage applied to a circuit (e.g., an inverter) included in the power transmitting unit 103 and the voltage across the resonant capacitor 107 may be measured, and the voltage applied to the power transmitting antenna may be calculated from the results.

In other words, it is possible to obtain the coupling state index from the measurement results of the transmission voltage applied to the circuit (e.g., inverter) included in the power transmitting unit 103 and the voltage applied across the resonant capacitor 107. In this case, the transmission voltage applied to the circuit (e.g., inverter) included in the power transmitting unit 103 may be calculated by the TX from the set value of the transmission power.

In addition, in FIG. 12(B), the current I1 or I2 is not limited to the current flowing through the power transmitting antenna, but may be, for example, a current flowing through a circuit (e.g., an inverter) included in the power transmitting unit 103. Here, the current flowing through a circuit included in the power transmitting unit 103 of the TX is, for example, an inverter input current or an inverter output current.

The open and short states of the power receiving antenna have been described as being realized by the control unit 201 controlling the second switch unit 210 and the third switch unit 213. These states may also be realized by the power receiving unit 203.

In addition, instead of the short state, a light load state may be used.In addition, instead of the open state, a connected load state may be used.

In the second measurement method, the TX can calculate the coupling state index by measuring the input voltages V6 and V7 and the currents I1 and I2. Therefore, information such as the voltage value measured by the RX or the inductance value of the receiving antenna is not required, so there is no need for the RX to notify the TX of this information.

However, when the TX measures the input voltage V6 and the current I1, the RX needs to keep both terminals of the circuit that includes the receiving antenna in SHORT. Also, when the TX measures the input voltage V7 and the current I2, the RX needs to keep both terminals of the circuit that includes the receiving antenna in OPEN.

In other words, depending on the timing at which the TX measures the input voltage and current, the RX needs to control both terminals of the circuit that contains the receiving antenna to be in a SHORT or OPEN state.

Once this control is complete, the TX performs the measurement. The timing of the measurement is determined by the TX and notified to the RX, or the RX determines and notifies the TX. The RX also notifies the TX when it has completed the control to set both terminals of the circuit that includes the receiving antenna to the SHORT or OPEN state.

These notifications are sent by communication based on the WPC standard between the first communication unit 104 of the TX and the first communication unit 204 of the RX, or by communication based on a standard other than the WPC standard between the second communication unit 109 of the TX and the second communication unit 212 of the RX.

The input voltages V6, V7 and currents I1, I2 are measured, for example, during the Ping phase. During the Ping phase, the TX transmits a DP to the RX. Therefore, the values of V6, V7 and currents I1, I2 generated when the DP is transmitted can be used.

In the Ping phase, the TX acquires the values of V6, V7, I1, and I2, stores them in memory 106, and calculates the coupling state index. Note that the present invention is not limited to the example in which the TX uses the voltage values and current values generated when transmitting a DP.

For example, the values of V6, V7, I1, and I2 that are generated when the TX transmits to the AP in the Selection phase may be used. Alternatively, the voltage values of V6, V7, I1, and I2 that are generated when the TX transmits power to the RX in the Power Transfer phase may be used.

In this disclosure, either the first measurement method or the second measurement method can be applied to the method of measuring the coupling status index of the transmitting antenna and the receiving antenna. Below, a method of setting a status determination threshold for the coupling status index obtained by the first or second measurement method is described.

The status determination includes a determination regarding the detection of a foreign object between the power transmitting antenna and the power receiving antenna, a determination regarding the detection of a misalignment between the power transmitting antenna and the power receiving antenna, and a determination regarding the detection of the separation between the power transmitting antenna and the power receiving antenna.

It is possible to carry out the first or second measurement and determine the presence or absence of a condition abnormality using a condition determination threshold. The first to fourth threshold setting methods are described below.

The first threshold setting method is a method in which the value of the coupling status index in a state where there is no abnormality is set as the threshold for the coupling status index used to detect the status between the transmitting antenna and the receiving antenna. In status detection, a determination result such as "abnormal status exists," "high possibility of abnormal status," "low possibility of abnormal status," "no abnormal status," etc. is obtained.

Assume that the RX is placed on the test TX and there is no abnormality in the state between the transmitting antenna and the receiving antenna. In this case, the value of the coupling state index between the test TX including the transmitting antenna and the RX including the receiving antenna can be set as the threshold value.

The RX holds the value (threshold) of the coupling status index measured in advance in memory, and notifies the TX of the threshold. The TX uses the threshold to perform a determination process regarding status detection. The RX may transmit this threshold to the TX within the FOD Status Data packet defined in the WPC standard.

Alternatively, the value of the coupling state index between the transmitting antenna and the receiving antenna at which a certain power transmission efficiency is obtained may be set as the threshold value. In state detection, for example, the following judgment results are obtained.

- "The specified power transmission efficiency cannot be obtained" or "The coupling between the power transmitting antenna and the power receiving antenna is weak."
- "There is a high possibility that the specified power transmission efficiency will not be achieved," or "The coupling between the power transmitting antenna and the power receiving antenna may be weak."
- "There is a high possibility that a specified power transmission efficiency can be obtained," or "There is a high possibility that the coupling state between the power transmitting antenna and the power receiving antenna is good."
- "A predetermined power transmission efficiency is obtained" or "The coupling state between the power transmitting antenna and the power receiving antenna is good."

Here, we assume that the RX is placed on the test TX, there are no abnormal conditions between the transmitting antenna and the receiving antenna, and a specified power transmission efficiency is obtained. In this case, the value of the coupling condition index between the test TX including the transmitting antenna and the RX including the receiving antenna can be set as the threshold value.

The RX holds the previously measured value of the coupling status index in memory as a threshold value, and notifies the TX of the threshold value. The TX uses the threshold value to perform a determination process related to status detection. The RX may transmit this threshold value to the TX within the FOD Status Data packet defined in the WPC standard.

The second threshold setting method is a method in which the TX and RX set the coupling status index measured by the first or second measurement method as the threshold in a specified state. The specified state is "a state in which there is no abnormality between the transmitting antenna and the receiving antenna."

The method for checking this state can utilize detection of the state of the TX and RX, such as foreign object detection using the power loss method, foreign object detection using the waveform attenuation method, foreign object detection using the Q value measurement method, or foreign object detection based on the temperature of the TX or RX, which will be described later.

If it is determined that there is no abnormal condition as a result, it can be confirmed with a high degree of probability that there is "no abnormal condition between the transmitting antenna and the receiving antenna." In other words, this confirmation is performed by a method and means other than the first or second measurement method.

If the result is that there is "no abnormal condition" (or "no foreign matter"), the bond condition index is measured using the first or second measurement method, and an appropriate threshold is set based on the measurement result.

For example, in the WPC standard, a foreign object detection process using a Q-value measurement method is executed in the Negotiation phase or Renegotiation phase. If the result of the foreign object detection process is that there is "no abnormal state" (or "no foreign object"), the bond state index is measured using the first or second measurement method after the Negotiation phase or Renegotiation phase.

Based on the measurement results, it is possible to set a more appropriate threshold value. Furthermore, the foreign object detection process using the Power Loss method is executed during the Power Transfer phase. After the foreign object detection process is executed, the binding state index is measured using the first or second measurement method, and based on the measurement results, it is possible to set a more appropriate threshold value.

Alternatively, the TX can use the AP or DP transmitted by the TX in the Selection phase or Ping phase to perform foreign object detection processing using a Quality Factor measured by the waveform attenuation method, etc.

In this case, the binding state index is measured using the first or second measurement method after the phase in which the foreign object detection process is performed, and an appropriate threshold value can be set based on the measurement results.

Alternatively, the foreign object detection process using the waveform attenuation method described above is performed during the power transfer phase. After the foreign object detection process is performed, the binding state index is measured using the first or second measurement method, and a more appropriate threshold value can be set based on the measurement result.

Next, the third threshold setting method will be described with reference to FIG. 13. FIG. 13 is a diagram for explaining a threshold setting method for state detection using a coupling state index. In FIG. 13, the horizontal axis represents the transmitted power, and the vertical axis represents the coupling state index.

On the graph line indicated by the straight line segment 1202, point 1200 corresponds to the transmission power value Pt1 and the coupling state index value k1, and point 1201 corresponds to the transmission power value Pt2 and the coupling state index value k2.

On the graph line, point 1203 corresponds to the transmission power value Pt3 and the coupling state index value k3. The first or second measurement method described above can be used to calculate each coupling state index value.

As shown in FIG. 3, the charging unit 206 and the battery 207 are connected as loads to the RX power receiving unit 203, so the calculated coupling state index value changes depending on the load state. In order to determine the presence or absence of a state abnormality depending on the load state, it is necessary to set a threshold value for the coupling state index.

First, when power is transmitted from the TX, the RX controls the load so that it is in a light load state. A light load state is a state in which no power is supplied to the RX load, or only power below a threshold is supplied.

Or it is a load state in which the received power value of the RX is within a predetermined range (hereinafter referred to as the "fifth range"). The transmitted power value of the TX in this state is Pt1. Then, the RX transmits a packet to the TX requesting that a measurement of the coupling state indicator be performed.

Alternatively, the TX sends a packet to the RX requesting that a coupling status indicator measurement be performed. In this state, the TX and RX perform measurements of the transmission voltage on the TX side and the receiving voltage on the RX side.

The TX and RX exchange information such as the values of V1 to V7, the self-inductances L1 and L2, or constants calculated using the electrical characteristics of the transmitting and receiving antennas, and the TX or RX calculates the coupling state index value k1.

When RX calculates the coupling state index value k1, it notifies TX of the result. When TX calculates the coupling state index value k1, it notifies RX of the result and Pt1. At this time, TX recognizes the transmission power value Pt1, and stores CP1200 that associates Pt1 and k1 in memory.

Alternatively, the RX stores in memory CP1200 that associates Pt1 with k1. Next, the RX controls the RX load so that it is in a load-connected state when power is transmitted from the TX. The load-connected state is a state in which maximum power is supplied to the RX load, or power equal to or greater than a threshold is supplied.

Here, "maximum power" refers to a power value close to the Reference Power. Or, it is a load state in which the RX receiving power value is within a predetermined range (hereinafter referred to as the "sixth range").

Here, the sixth range is a range of power values higher than the fifth range. The transmission power value of the TX in this state is Pt2. Then, the RX transmits a packet to the TX requesting that a measurement of the coupling status indicator be performed. Alternatively, the TX transmits a packet to the RX requesting that a measurement of the coupling status indicator be performed.

In this state, the TX and RX measure the transmission voltage on the TX side and the receiving voltage on the RX side. The TX and RX exchange information such as the above values of V1 to V7, the values of self-inductance L1 and L2, or constants calculated using the electrical characteristics of the transmitting antenna and receiving antenna, and the TX or RX calculates the coupling state index value k2.

When RX calculates the binding state index value k2, it notifies TX of the result. When TX calculates the binding state index value k2, it notifies RX of the result and Pt2. TX stores in memory CP1201 that associates Pt2 and k2.

Alternatively, RX stores in memory CP1201 that associates Pt2 and k2. TX then performs linear interpolation between CP1200 and CP1201 to generate line segment 1202.

Line 1202 shows the relationship between the transmission power and the coupling state index when there are no abnormal conditions around TX and RX. TX can use line 1202 to estimate the coupling state index value for each transmission power value when there are no abnormal conditions around TX and RX.

For example, assume that the transmission power value is Pt3. In this case, the coupling state index value k3 can be estimated from point 1203 on line segment 1202 that corresponds to the transmission power value Pt3. Based on the estimation result, the TX can calculate a threshold value used to determine the presence or absence of a state abnormality for each transmission power value.

For example, the coupling state index value obtained by adding a predetermined value (a value corresponding to the measurement error) to the estimated result of the coupling state index value when there is no abnormality at a certain transmission power value can be set as the judgment threshold value.

The calibration process performed by the power transmission device 100 and the power receiving device 200 in this manner in order for the power transmission device 100 to obtain a combination of the transmission power value and the coupling state index value is called the "CAL process of the coupling state index measurement method." In addition, the power transmission device 100 and the power receiving device 200 can perform the CAL process of the coupling state index measurement method multiple times.

　The CAL process of the binding status index measurement method that is performed again after the CAL process of the binding status index measurement method has been performed once is referred to as the "recalibration process of the binding status index measurement method" below.

The recalibration process is abbreviated as RECAL process. Note that the RX may perform the control to put the load into a light load state and the control to put the load into a connected state after notifying the TX that the control will be performed. Also, either of these two controls may be performed first.

In this embodiment, the operation for calculating the judgment threshold for state detection for each load (or each transmission power value) is performed, for example, in the calibration phase. In this phase, the TX acquires data required for foreign object detection using the power loss method.

At that time, the TX acquires data on the amount of power loss when the RX is in a light load state and when the RX is in a loaded state. Therefore, the measurements of CP1200 and CP1201 in FIG. 13 can be performed together with the measurement of power loss when the RX is in a light load state and when it is in a loaded state during the calibration phase.

In other words, when the TX receives the first reference received power information from the RX, in addition to the predetermined processing to be performed in the calibration phase, the TX measures CP1200. The first reference received power information is information according to RP1 defined in the WPC standard, but other messages may also be used.

Furthermore, when the TX receives the second reference received power information from the RX, in addition to the predetermined processing to be performed in the calibration phase, it measures CP1201. The second reference received power information is information by RP2 defined in the WPC standard, but other messages may be used. In this way, there is no need to set aside a separate period for measuring CP1200 and CP1201, so that CP1200 and CP1201 can be measured in a shorter time.

The fourth threshold setting method is a method in which the TX or RX sets a threshold in advance for a coupling state indicator that has a value within a predetermined range. The TX or RX holds a predetermined value for this threshold as a common value that is not dependent on the RX that is the target of power transmission.

The threshold value may be a fixed value that does not depend on the situation, or a variable value that is determined by the TX or RX depending on the situation. For example, if the coupling state index is the coupling coefficient k, the range of the k value is "0≦k≦1".

For example, TX or RX will determine that "there is a status abnormality" when "0≦k<0.2" and that "there is a high possibility of a status abnormality" when "0.2≦k<0.5". TX or RX will determine that "there is a low possibility of a status abnormality" when "0.5≦k<0.8" and that "there is no status abnormality" when "0.8≦k≦1".

The condition data for the k value is stored in advance in memory, and the decision-making process is carried out based on that data.

Alternatively, for example, if "0≦k<0.2", the TX or RX determines that "the specified power transmission efficiency cannot be obtained" or that "the coupling between the transmitting antenna and the receiving antenna is weak."

If "0.2≦k<0.5", the TX or RX determines that "there is a high possibility that the specified power transmission efficiency will not be achieved" or "there is a possibility that the coupling between the transmitting antenna and the receiving antenna is weak."

If "0.5≦k<0.8", the TX or RX determines that "there is a high possibility that the specified power transmission efficiency is obtained" or "there is a high possibility that the coupling state between the transmitting antenna and the receiving antenna is good."

The TX or RX determines that "a certain power transmission efficiency is obtained" or "the coupling state between the transmitting antenna and the receiving antenna is good" when "0.8≦k≦1." The condition data for the k value is stored in memory in advance, and the determination process is performed based on that data.

In addition, when setting a judgment threshold for state detection using a binding state index, a value obtained by adding a predetermined value (a value corresponding to a measurement error) to the binding state index value calculated based on the measurement results or received information can be set as the judgment threshold. As mentioned above, the threshold is not limited to one, and multiple thresholds can be set in stages.

Next, the timing for calculating the coupling state between the transmitting antenna and the receiving antenna using the first or second measurement method will be described. The calculation (measurement) of the coupling state index is performed by the RX transmitting a predetermined packet to the TX.

Here, the specified packet is a Signal Strength Data packet that RX sends to TX. Alternatively, it may be an Identification Data packet, Extended Identification Data packet, or Configuration Data packet in the I&C phase.

Or it may be a packet in the calibration phase or power transfer phase. In other words, it may be RP1, RP2, or RP0.

When the TX receives a specified packet from the RX, it calculates the coupling status index between the transmitting antenna and the receiving antenna. The TX then makes a judgment by comparing the calculated coupling status index with the judgment threshold set by the above method.

If the TX judges that there is no abnormal status, it sends a positive response ACK to the RX, or status information indicating that there is no abnormal status to the RX. If the TX judges that there is a low possibility of an abnormal status or that there is a high possibility of an abnormal status, it sends status information indicating the respective judgment result to the RX.

If the TX determines that there is an abnormal status, it sends a negative acknowledgement NAK to the RX, or status information indicating that there is an abnormal status to the RX.

Alternatively, if the TX determines that "a specified power transmission efficiency can be obtained" or "the coupling state between the transmitting antenna and the receiving antenna is good," it transmits an ACK to the RX or status information indicating the determination result to the RX.

If the TX determines that "there is a high probability that the specified power transmission efficiency is achieved" or "the coupling state between the transmitting antenna and the receiving antenna is likely to be good," it transmits status information indicating the determination result to the RX.

If the TX determines that "there is a high possibility that the specified power transmission efficiency will not be achieved" or "the coupling between the transmitting antenna and the receiving antenna may be weak," it transmits status information indicating the result of the determination to the RX.

If the TX determines that "the specified power transmission efficiency cannot be achieved" or that "the coupling between the transmitting antenna and the receiving antenna is weak," it sends a negative response NAK to the RX, or status information indicating the determination result to the RX.

The state information is, for example, numerical information according to the state, as follows:
Status information "0" corresponds to the determination result that "there is no status abnormality", or "a predetermined power transmission efficiency is obtained", or "the coupling state between the power transmitting antenna and the power receiving antenna is good".
- Status information "1" corresponds to the determination result that "there is a low possibility of a status abnormality", or "there is a high possibility of obtaining a specified power transmission efficiency", or "there is a possibility that the coupling state between the transmitting antenna and the power receiving antenna is good".
Status information "2" corresponds to the judgment result that "there is a high possibility of a status abnormality", or "there is a high possibility that the specified power transmission efficiency cannot be obtained", or "there is a possibility that the coupling between the transmitting antenna and the power receiving antenna is weak".
Status information "3" corresponds to a determination result of "there is an abnormal status", or "the specified power transmission efficiency is not obtained", or "the coupling between the power transmitting antenna and the power receiving antenna is weak".

Alternatively, the calculation (measurement) of the coupling status indicator is performed by the TX transmitting a predetermined packet to the RX. The predetermined packet is a Power Transmitter Capabilities (CAP) Data Packet transmitted by the TX to the RX.

Or, it is a Power Transmitter Identification (ID) data packet. When the RX receives a specified packet from the TX, it calculates a coupling status index between the transmitting antenna and the receiving antenna.

Then, the RX judges the state by comparing the judgment threshold set by the above method with the calculated coupling state index. If the RX judges that there is no abnormal state, it transmits a specified packet including state information indicating the judgment result to the TX.

If the RX judges that "the possibility of a status abnormality is low" or "the possibility of a status abnormality is high," it transmits a specified packet containing status information indicating the respective judgment result to the TX. If the RX judges that "there is a status abnormality," it transmits a specified packet containing status information indicating the judgment result to the TX.

Alternatively, if the RX determines that "a specified power transmission efficiency is achieved" or "the coupling state between the transmitting antenna and the receiving antenna is good," it transmits status information indicating the determination result to the TX.

If the RX determines that "there is a high possibility that the specified power transmission efficiency can be achieved" or "the coupling state between the transmitting antenna and the receiving antenna is likely to be good," it transmits status information indicating the determination result to the TX.

If the RX determines that "there is a high possibility that the specified power transmission efficiency will not be achieved" or "the coupling between the transmitting antenna and the receiving antenna may be weak," it transmits status information indicating the result of the determination to the TX.

If the RX determines that "the specified power transmission efficiency cannot be achieved" or that "the coupling between the power transmitting antenna and the power receiving antenna is weak," it transmits status information indicating the determination result to the TX. Examples of the status information are as described above.

Next, a method for detecting a foreign object based on the temperature of the TX or RX will be described. The TX and RX each have temperature sensors at multiple locations. In particular, temperature sensors are placed at a higher density on the transmitting antenna 105 and charging stand 300, and on the receiving antenna 205, compared to other locations.

It is now possible to detect foreign objects present between the TX and RX with higher accuracy. The TX or RX executes a foreign object detection process based on the detected temperature. The TX acquires the detection value of the temperature sensor at a specified timing.

The specified timing occurs at a predetermined cycle or when the TX receives a specified packet from the RX. If the temperature sensor detection value is greater than the threshold, the TX determines that there is a high possibility that a foreign object is present.

The TX also calculates the rate of temperature rise based on multiple temperature detection values acquired at a specified timing. If the rate of temperature rise is greater than a threshold value, the TX determines that there is a high possibility that a foreign object is present.

The determination result is notified to the RX in a specified packet. Alternatively, when the determination result is obtained, the TX performs the control to limit the power transmission described above (stopping power transmission or reducing the transmission power).

Next, we will explain the foreign object detection process based on the temperature of the RX. The RX acquires the detection value of the temperature sensor at a specified timing. The specified timing occurs at a predetermined cycle or when the RX receives a specified packet from the TX.

If the temperature sensor detection value is greater than the threshold value, the RX determines that there is a high possibility that a foreign object is present. The RX also calculates the temperature rise rate based on multiple temperature detection values acquired at a specified timing.

If the rate of temperature rise is greater than the threshold, the RX determines that there is a high possibility that a foreign object is present. The RX notifies the TX of the determination result in a specified packet. Alternatively, when the determination result is obtained, the RX transmits a specified packet to the TX to request a restriction on power transmission (stopping power transmission or reducing the transmission power).

Next, we will explain a method for detecting a foreign object based on a current value related to the current flowing through the TX transmitting antenna (hereinafter referred to as the first current value) or a current value related to the current flowing through the RX receiving antenna (hereinafter referred to as the second current value).

The TX or RX executes a foreign object detection process based on the detected first or second current value. The TX acquires the first current value at a specified timing. The specified timing occurs at a predetermined cycle or when the TX receives a specified packet from the RX.

If the first current value is greater than the threshold value, the TX determines that there is a high possibility that a foreign object is present. The TX also calculates the rate of increase in the current value based on the first current value acquired at a predetermined timing.

If the rate of increase in the current value is greater than a threshold, the TX determines that there is a high possibility that a foreign object is present. The result of this determination is notified to the RX in a specified packet. Alternatively, when the result of this determination is obtained, the TX performs control to limit the power transmission (stopping power transmission or reducing the transmission power).

Next, the foreign object detection process based on the second current value in the RX will be described. The RX acquires the second current value at a predetermined timing. The predetermined timing occurs at a predetermined cycle or when the RX receives a predetermined packet from the TX.

If the second current value is greater than the threshold value, the RX determines that there is a high possibility that a foreign object is present. The RX also calculates the rate of increase in the current value based on the second current value acquired at a specified timing. If the rate of increase in the current value is greater than the threshold value, the RX determines that there is a high possibility that a foreign object is present.

The result of this determination is notified to the TX in a specified packet. Alternatively, when the result of this determination is obtained, the RX transmits a specified packet to the TX and performs processing to request a restriction on power transmission (stopping power transmission or reducing the transmission power). By measuring the first or second current value as described above, more accurate foreign object detection is possible based on the measurement result.

When detecting abnormalities in the status of the TX or RX, the TX and RX may perform a combination of multiple foreign object detection processes. In other words, the Q value measurement method, the power loss method, the waveform attenuation method, the coupling status index measurement method, foreign object detection process based on temperature, and foreign object detection process based on the current flowing through the transmitting antenna or the receiving antenna may be combined.

The foreign object detection process based on the coupling state indicator measurement method is referred to as the first foreign object detection process, the foreign object detection process based on the TX temperature is referred to as the second foreign object detection process, and the foreign object detection process based on the current flowing through the transmitting antenna is referred to as the third foreign object detection process.

The entity that executes the first to third foreign object detection processes is the TX. In this case, the TX executes a foreign object detection process selected from the first to third foreign object detection processes, and notifies the RX of the foreign object determination result. If the foreign object determination result is "high possibility of foreign object presence" or "foreign object present", the RX notifies the TX of a packet requesting the execution of a specified foreign object detection process.

The specified foreign object detection process is a foreign object detection process based on one or more of the following methods: the Q-value measurement method, the Power Loss method, and the waveform attenuation method. The TX executes the specified foreign object detection process according to an execution request from the RX, and notifies the RX of the foreign object determination result.

If the foreign object determination result is "high possibility of foreign object presence" or "foreign object present," RX transmits to TX a packet requesting a limit on power transmission or a packet requesting the above-mentioned RECAL processing. A packet requesting a limit on power transmission or a packet requesting the above-mentioned RECAL processing (hereinafter, these packets are referred to as a limit request packet) is, for example, a packet requesting that the GP value be set to a lower value, or RP1 or RP2 requesting RECAL processing using the Power Loss method.

Or, it is a packet for requesting a RECAL process of the waveform decay method or a RECAL process of the coupling condition index measurement method. Or, it is an EPT packet for requesting the stop of power transmission.

Alternatively, the TX executes a foreign object detection process based on one or more of the Q-value measurement method, the Power Loss method, and the waveform attenuation method, and notifies the RX of the foreign object determination result. If the foreign object determination result is "highly likely to have a foreign object" or "foreign object exists," the RX transmits a packet to the TX requesting the execution of a foreign object detection process selected from the first to third foreign object detection processes.

The TX executes one or more of the first through third foreign object detection processes according to the packet, and notifies the RX of the foreign object determination result. If the foreign object determination result is "highly likely to have a foreign object" or "foreign object exists," the RX sends a restriction request packet to the TX.

Furthermore, the foreign object detection process based on the temperature of the RX is referred to as the fourth foreign object detection process, and the foreign object detection process based on the current flowing through the power receiving antenna is referred to as the fifth foreign object detection process. The subject that executes the first, fourth, and fifth foreign object detection processes is the RX.

In this case, the RX executes a foreign object detection process selected from the first, fourth, or fifth foreign object detection process, and notifies the TX of the foreign object determination result. If the foreign object determination result is "high probability of foreign object presence" or "foreign object present," the RX notifies the TX of a packet requesting the execution of a specified foreign object detection process.

The specified foreign object detection process is a foreign object detection process based on one or more of the following methods: the Q-value measurement method, the Power Loss method, and the waveform attenuation method. The TX executes the specified foreign object detection process in response to a request from the RX, and notifies the RX of the foreign object determination result.

If the result of the foreign object detection process is "high probability that a foreign object exists" or "foreign object exists," the RX sends a restriction request packet to the TX.

Alternatively, the TX executes a foreign object detection process based on one or more of the Q-value measurement method, the Power Loss method, and the waveform attenuation method, and notifies the RX of the foreign object determination result. The foreign object determination result is assumed to be "highly likely that a foreign object exists" or "a foreign object exists."

In this case, the RX acquires the coupling status indicator, or the temperature detection value of the RX, or the current value flowing through the RX's power receiving antenna, executes a foreign object detection process, and notifies the TX of the foreign object determination result. If the foreign object determination result is "highly likely to have a foreign object" or "foreign object exists," the RX transmits a restriction request packet to the TX.

In the above example, the TX or RX executes the first foreign object detection process, the second or fourth foreign object detection process, the third or fifth foreign object detection process, and other foreign object detection processes at different times. The other foreign object detection processes are foreign object detection processes based on one or more of the Q-value measurement method, the Power Loss method, and the waveform attenuation method.

Without being limited to this example, the TX or RX may execute the first foreign object detection process, the second or fourth foreign object detection process, the third or fifth foreign object detection process, and other foreign object detection processes at the same time.

If the timing is specified by the RX (or TX), the RX (or TX) notifies the TX (or RX) of the timing by transmitting a specified packet to the TX (or RX). For example, when the TX (or RX) receives a specified packet, it executes the second (or fourth) foreign object detection process and foreign object detection process using the Power Loss method.

Alternatively, when the TX (or RX) receives a specified packet, it executes a second (or fourth) foreign object detection process and a foreign object detection process using the waveform attenuation method.

Alternatively, when the TX (or RX) receives a specified packet, it executes the second (or fourth) foreign object detection process, the foreign object detection process using the power loss method, and the foreign object detection process using the waveform attenuation method. Any combination of foreign object detection processes is possible, and the combination can be changed according to the settings of predetermined conditions, etc.

In the above example, the restriction request packet is "a packet requesting a restriction on power transmission, or a packet requesting the above-mentioned RECAL process." However, the above-mentioned restriction request packet may be interpreted as two packets, "a packet requesting a restriction on power transmission, and a packet requesting the above-mentioned RECAL process."

In this embodiment, one of the multiple foreign object detection processes described above is performed as a state detection process based on a measurement process (CAL process) of a physical quantity related to the power transmission device. Whether or not to limit power transmission or perform RECAL process is determined based on information acquired during the first state detection and information acquired during the second state detection based on a measurement process executed after the measurement process executed during the first state detection.

The power transmitting device determines that the power receiving device should request the power transmitting device to execute RECAL processing. In this case, the power transmitting device transmits the detection result related to the first or second state detection and information related to the request to execute RECAL processing to the power receiving device. According to this embodiment, it is possible to perform more suitable control based on multiple state detection results in wireless power transmission from the power transmitting device to the power receiving device.

[Second embodiment]
Next, a second embodiment will be described. In the first embodiment, the Q value measurement method, the power loss method, the waveform attenuation method, the coupling state index measurement method, the foreign object detection method based on temperature, and the foreign object detection method based on the current flowing through the power transmitting antenna or the power receiving antenna have been described.

The "condition detection method" of this disclosure refers to these methods, and any of these methods may be used. The foreign object detection method is one example of a condition detection method. "The presence of a foreign object" can be said to be "the presence of an abnormal condition."

For example, the expression "detected the presence of a foreign object" in the first embodiment will be expressed as "detected an abnormal condition" below. Note that in this embodiment, explanations of matters similar to those in the first embodiment will be omitted, and differences will be mainly explained. This method of omitting explanations will be the same in the embodiments described below.

The following describes the operation of the TX and RX when the TX executes the status detection method and detects an abnormal status. Figure 14 is a flowchart that explains the operation of the TX. Figure 15 is a flowchart that explains the operation of the RX.

Processing starts at S1401 in FIG. 14, and the TX is powered ON at S1402. After the Selection phase and Ping phase, the TX detects the RX at S1403. After the I&C phase, Negotiation phase, and Calibration phase, the TX starts transmitting power to the detected RX in the Power Transfer phase at S1404. Processing then proceeds to S1405.

In S1405, the TX determines whether or not it has received an execution request packet for the state detection method (FIG. 15: S1506) from the RX. The execution request packet will be described later. If the TX has not received the execution request packet (No in S1405), it continues power transmission and repeatedly executes the determination process of S1405. If the TX has received the execution request packet (Yes in S1405), it proceeds to the process of S1406.

In S1406, the TX executes a state detection method, measures a physical quantity related to the TX, and compares the measurement result with a threshold value to determine whether or not a state abnormality exists. For example, when the TX executes the state detection method, it determines the possibility (probability) of a state abnormality in stages. The determination results are shown below.

- <State 1>: The physical quantity measured by the TX is significantly lower than the threshold value, and the possibility of a status abnormality is very low.
<State 2>: The physical quantity measured by the TX is slightly below the threshold value, and the possibility of an abnormal condition is low.
<State 3>: The physical quantity measured by the TX is slightly above the threshold value, and there is a high possibility of an abnormal condition.
- <State 4>: The physical quantity measured by the TX is significantly higher than the threshold value, and there is a "high possibility of an abnormal status."
In this example, if the physical quantity measured by TX exceeds a threshold value, it is determined that there is a possibility of a status abnormality.

In another example, if the physical quantity measured by the TX falls below a threshold, it is determined that there is a possibility of a status abnormality. The determination results are shown below.

<State 1>: The physical quantity measured by the TX is significantly higher than the threshold, and the possibility of an abnormal condition is very low.
- <State 2>: The physical quantity measured by the TX is slightly above the threshold value, and the possibility of a status abnormality is low.
<State 3>: The physical quantity measured by the TX is slightly below the threshold value, and there is a high possibility of an abnormal state.
- <State 4>: The physical quantity measured by the TX is significantly lower than the threshold value, and there is a "high possibility of an abnormal status."
In this example, <State 3> and <State 4> are states in which the physical quantity measured by the TX is outside the range based on the threshold value, and it is determined that there is a possibility of an abnormal state, but power transmission from the TX to the RX is possible.

After S1406, in S1407, the TX determines whether or not there is a possibility of a status abnormality as a result of executing the status detection method. If the TX determines that there is no possibility of a status abnormality or that the possibility of a status abnormality is low (No in S1407), the TX proceeds to S1405 and continues transmitting power to the RX.

For example, a case where it is determined that "the possibility of a status abnormality is low" is when the above-mentioned <Status 1> or <Status 2> is detected. On the other hand, when the TX determines that there is a possibility of a status abnormality (Yes in S1407), it proceeds to the processing of S1408. For example, a case where it is determined that "the possibility of a status abnormality" is when the above-mentioned <Status 3> or <Status 4> is detected.

In S1408, TX transmits a packet to RX requesting permission to notify (communicate) information. Alternatively, in S1408, TX transmits a packet to RX requesting attention.

For example, the packet in question is a response (ATN) defined in the WPC standard. When the RX receives the ATN sent by the TX, it sends a packet to the TX that allows it to send a Data packet.

Alternatively, when the RX receives the ATN sent by the TX, it sends a packet to the TX requesting the transmission of a Data packet. Specifically, the packet is a DSR/poll packet or a DSR/poll Data packet as defined by the WPC standard.

In S1409, the TX determines whether or not it has received a DSR/poll packet or a DSR/poll data packet from the RX. If the TX has not received the packet from the RX (No in S1409), it continues transmitting power and repeats the determination process of S1409. If the TX has received the packet from the RX (Yes in S1409), it proceeds to the process of S1410.

At S1410, the TX transmits a status detection result packet to the RX. The status detection result packet is a packet that includes information indicating the result of the TX executing the status detection method. For example, the TX notifies the RX by including the following first information about the status detection method in the status detection result packet.

Information indicating which state detection method was executed.
・Information indicating the possibility of a status abnormality.
- Index information (for example, any one of <State 1> to <State 4>) that indicates the result of comparing the measured physical quantity with a threshold value.

Status detection methods include the Q value measurement method, the power loss method, the waveform attenuation method, the coupling status index measurement method, a foreign object detection method based on temperature, and a foreign object detection method based on the current flowing through the transmitting antenna or the receiving antenna.

The first information includes information indicating which of these condition detection methods was used to detect the condition. The first information also includes index information indicating the possibility of a condition abnormality as a result of the condition detection using that condition detection method. The index information can also be considered as information on the result of comparing the measured physical quantity with a threshold value.

Next, in S1411, TX transmits a RECAL processing request packet to RX. The RECAL processing request packet is a packet that includes information requesting RECAL processing. For example, TX notifies RX of the following second information regarding the RECAL processing request by including it in the RECAL processing request packet.

Information indicating whether or not to request execution of a RECAL process of the Power Loss method.
Information indicating whether or not to request execution of RECAL processing of the waveform decay method.
Information indicating whether or not to request execution of a RECAL process for the binding status indicator measurement method.
Information indicating the type of RECAL process which requests the execution of the power loss method, the waveform decay method, or the coupling condition index measurement method.

Here, "RECAL process type" refers to the first or second RECAL process below.

First RECAL process: Any existing calibration points or lines that have been interpolated between calibration points are discarded. The RX retransmits RP1 and RP2 to the TX, and the TX creates new calibration points or lines that have been interpolated between calibration points.

Second RECAL process: The existing calibration points or the line segments obtained by interpolating between the calibration points are maintained. The RX transmits RP2 to the TX, and the TX adds new calibration points to the existing calibration points or the line segments obtained by interpolating between the calibration points.

For example, assume that the TX executes the status detection method and determines that "there is a high possibility of a status abnormality" or "there is a very high possibility of a status abnormality."

The occurrence of a status abnormality may cause deviations in calibration points created by CAL processing performed when the probability of a status abnormality is low, or in lines interpolated between calibration points.

Therefore, it is necessary to perform RECAL processing depending on the possibility of a status abnormality. Therefore, the second information includes information on whether or not to request execution of RECAL processing. Furthermore, the second information includes information indicating which status detection method the RECAL processing is for.

Next, in S1412, TX receives a RECAL processing execution request packet from RX. The execution request packet is, for example, RP1 or RP2. In S1413, TX executes RECAL processing based on the information in the received RECAL processing execution request packet.

The counter variable that counts the number of times the RECAL process has been executed is denoted as A. In S1414, TX increases (increments) the value of variable A by 1. Then, the process proceeds to S1415.

In S1415, the TX determines whether the value of counter variable A is equal to or greater than a predetermined number of times (threshold value). If the TX determines that the value of variable A is equal to or greater than the predetermined number of times (Yes in S1415), the TX proceeds to processing in S1416.

Also, if it is determined that the value of variable A is less than the predetermined number of times (No in S1415), the process proceeds to S1405, and the TX continues transmitting power to the RX. In S1416, the TX performs control to limit the transmission power (control to limit the power received by the RX), and ends the series of processes in S1417.

Next, the operation of the RX will be described with reference to FIG. 15. Processing starts in S1501, and the power of the RX is turned ON in S1502. When the RX is placed on the TX in S1503, the RX goes through the Selection phase and Ping phase, and is then detected by the TX.

After the I&C phase, the Negotiation phase, and the Calibration phase, in S1504 the RX starts receiving power transmitted from the TX in the Power Transfer phase.

Next, in S1505, RX determines whether to request TX to execute the state detection method. If the predetermined conditions are met (Yes in S1505), RX decides to request TX to execute the state detection method, and proceeds to processing in S1506.

On the other hand, if the specified condition is not met (No in S1505), the RX decides not to request the TX to execute the state detection method, continues receiving power, and repeats the process of S1505.

The "predetermined condition" in S1505 will now be explained. This condition is, for example, that the TX or RX has detected one or more of the following:

- An error occurred in the communication between TX and RX.
- A decrease in the power transmitted from TX to RX was observed.
- The acquired calibration data is an abnormal value.
- An increase in temperature is observed in the TX and/or RX.
- There is a high possibility that a status abnormality exists in the status detection method.
The RX receives information from the TX indicating that there is a high possibility that a status anomaly exists in the status detection method.

Alternatively, the "predetermined condition" corresponds to the following case.
When the transmission power transmitted from TX to RX is to be increased or decreased.
When information (setting value) regarding the transmission power of the TX or information (setting value) regarding the receiving power of the RX held by the TX or RX is changed.
When a measurement process (CAL process) is performed to set a threshold value used in executing the state detection method.
When the RX notifies the TX of the RX status (e.g., the power being received by the RX, etc.).

The above-mentioned "predetermined conditions" are preset in the RX. The RX decides to perform state detection when one or more of the set "predetermined conditions" are satisfied. Note that the "predetermined conditions" may be based on conditions other than those exemplified, or any arbitrary condition may be set.

The timing of executing the state detection method may be determined by the TX, not the RX, and the state detection method may be executed at the appropriate time. The TX can execute the state detection method at an appropriate timing that satisfies the "predetermined conditions."

In S1506, the RX transmits a request packet for executing the state detection method to the TX, and proceeds to the processing of S1507. Then, in S1507, the RX determines whether or not it has received an ATN (FIG. 14: S1408) from the TX.

If the RX receives an ATN from the TX (Yes in S1507), the process proceeds to S1508. If the RX does not receive an ATN from the TX (No in S1507), the RX continues receiving power, and the determination process of S1507 is repeated until an ATN is received.

In S1508, RX sends a packet (DSR/poll packet or DSR/poll data packet) to TX that allows TX to send a data packet.

In S1509, the RX determines whether or not it has received a status detection result packet (FIG. 14: S1410) from the power transmitting device. If it is determined in S1509 that the RX has received a status detection result packet from the TX, the process proceeds to S1510.

If it is determined that the status detection result packet has not been received, the determination process of S1509 is repeated until the packet is received. In S1510, RX determines whether or not it has received a RECAL processing request packet (FIG. 14: S1411) from TX.

If it is determined in S1510 that the RX has received a RECAL processing request packet from the TX, the process proceeds to S1511. If it is determined that the RECAL processing request packet has not been received, the determination process of S1510 is repeated until the packet is received.

In S1511, the RX sends a packet requesting execution of RECAL processing to the TX. In the next step, S1512, the RX determines whether or not it has received a packet from the TX to perform control to limit the transmission power.

If the RX determines that the packet has been received from the TX (Yes in S1512), it proceeds to the process of S1513. If the RX does not receive the packet from the TX (No in S1512), it proceeds to S1505 and continues receiving power.

In S1513, the RX performs control to limit the transmission power (control to limit the power received by the RX), and ends the series of processes in S1514.

In this embodiment, for example, it is assumed that TX transmits a status detection result packet to RX (FIG. 14: S1410) and then transmits an ATN to RX again (S1408).

In this case, when RX receives the ATN sent by TX (Figure 15: Yes in S1507), it sends a DSR/poll packet or a DSR/poll data packet to TX (S1508).

When the TX receives a DSR/poll packet or a DSR/poll data packet (Yes in S1409), it proceeds to the processing of S1411. In other words, the TX sends a RECAL processing request packet to the RX. This is also the case for the TX and RX in the third embodiment described later.

At least one of the pieces of information shown in the description of the first or second information above is transmitted from TX to RX. The first or second piece of information is determined based on information indicating the possibility of a status abnormality.

For example, if it is determined that there is a possibility of a status abnormality (<Status 3> or <Status 4>), the status detection result packet that the TX sends to the RX in S1410 of FIG. 14 includes the following information:

In the case of <State 3>, the first information includes information indicating the executed state detection method and information indicating that the state is "high possibility of abnormal state."
In the case of <State 4>, the first information includes information indicating the executed state detection method and information indicating that the state is "highly likely to be abnormal."

In addition, the RECAL processing request packet that TX sends to RX in S1411 of FIG. 14 includes the following information:

In the case of <State 3>, the second information includes information requesting execution of at least one RECAL process among the RECAL processes of the power loss method, the waveform decay method, and the binding condition index measurement method, and information requesting execution of a second RECAL process.

In the case of <State 4>, the second information includes information requesting execution of at least one RECAL process among the RECAL processes of the power loss method, the waveform decay method, and the binding condition index measurement method, and information requesting execution of the first RECAL process.

Alternatively, the TX may transmit the first and second information to the RX in the same packet. This allows the TX and RX to quickly and appropriately execute control according to the determination result when it is determined that "there is a status abnormality" or "there is a high possibility of a status abnormality."

Next, we will explain the control when the TX executes the state detection method multiple times and obtains a judgment result of <State 3> or <State 4> multiple times. If the judgment result is a state detected as "high possibility of abnormal state" or "very high possibility of abnormal state" (hereinafter also referred to as the second detection state), the RECAL process is executed.

Then, the TX executes the state detection method and again determines that it is in the second detection state. In this case, the TX executes the RECAL process again. Originally, the CAL process is a process that is executed when the first detection state is detected as having no abnormal state.

　Executing the RECAL process when in the second detection state means that the CP or the line segment where the interpolation between CPs is performed is changed. In other words, the ideal CP or the line segment where the interpolation between CPs is performed created in the CAL process is replaced with the CP or the line segment where the interpolation between CPs is performed in the second detection state.

If a possible abnormal state is detected multiple times, the RECAL process is executed multiple times. In this case, each time the RECAL process is executed, it will deviate from the CP in the first detection state or the line segment that was interpolated between the CPs.

As a result, if the reliability of the CP that serves as the reference for executing the condition detection method, or the line segments that are interpolated between CPs, decreases, it may become impossible to detect abnormal conditions with high accuracy.

Therefore, if the TX detects the second detection state multiple times and must execute the RECAL process (the first or second RECAL process) a predetermined number of times or more, the TX and RX limit the power transmitted by the TX or limit the power received by the RX. The method for limiting the power transmitted by the TX or the power received by the RX is as follows.

The TX requests to execute RECAL processing using the second information, and controls the transmission power of the TX using predetermined information (hereinafter referred to as the third information). The third information is information for controlling the transmission power of the TX so that it is equal to or lower than a predetermined power value.

Alternatively, the TX controls the maximum load power value that can be output (supplied) to the load of the RX so that it is equal to or less than a predetermined power value. Here, the predetermined power value is, for example, 5 (watts). Alternatively, the TX transmits to the RX predetermined information (hereinafter referred to as the fourth information) for switching the TX or RX mode. The fourth information is, for example, information indicating a request to switch to a mode that can transmit power only up to 5 watts.

Alternatively, if the RECAL process must be executed a predetermined number of times or more, the TX sends a packet to the RX requesting the transmission of an EPT packet. After receiving this packet, the RX sends an EPT packet to the TX, terminating the Power Transfer phase.

Alternatively, the TX detects the second detection state multiple times and requests the RX to perform the RECAL process a predetermined number of times or more. When the RX is requested to perform the RECAL process a predetermined number of times or more, it performs control to negotiate with the TX so that the value of GP becomes equal to or less than a predetermined power value.

Here, the specified power value is, for example, 5 (watts). Alternatively, the RX transmits to the TX a specified packet containing information requesting that the TX or RX mode be switched to a specified mode. The specified mode is the Basic Power Profile (BPP) mode defined in the WPC standard, which allows power transmission up to a maximum of 5 watts.

Here, we will explain the meaning of setting GP to 5 watts or less. If there is a foreign object between the TX and RX and the TX transmits power to the RX, the foreign object may generate heat.

The amount of heat generated by a foreign object increases as the power transmitted from the TX increases. Conversely, if the power transmitted by the TX (power received by the RX) is limited to a specified value or less, the amount of heat generated can be kept within a specified range (safe range).

In the WPC standard, even if foreign object detection is performed and there is a possibility that a foreign object is present, there are cases where power transmission from TX to RX is permitted if the GP is 5 watts or less. Therefore, it is possible to control power transmission by setting the above-mentioned specified power value to 5 (watts).

For the same reason, the transmission power of the TX is controlled to be 5 watts or less, or the maximum load power value that the TX can output (supply) to the load of the RX is controlled to be 5 watts or less. Alternatively, when a request is made to execute RECAL processing a predetermined number of times or more, the RX transmits an EPT packet to the TX and ends the Power Transfer phase.

The above-mentioned operations of TX and RX will be explained with reference to Fig. 14 to Fig. 16. Fig. 16 is a sequence diagram showing the operations of TX and RX, with the TX operation shown on the left and the RX operation shown on the right.

In the example of Figure 16, the power of the TX and RX are turned ON, and when the RX is placed on the TX, the Selection phase and the Ping phase are entered. The TX detects that the RX has been placed and starts transmitting power, and the RX starts receiving power.

After performing the measurement process (CAL process) related to status detection, the RX requests the TX to perform the status detection method, and the TX performs the status detection method according to the execution request from the RX. If it is determined that there is a possibility of an abnormality in the TX status, the TX transmits a packet containing information on the status detection result to the RX, and transmits a RECAL process request packet.

RX sends a RECAL processing execution request packet to TX. TX executes RECAL processing according to the execution request packet.

In S1410 of FIG. 14, TX transmits a status detection result packet to RX. If it is determined in S1509 that RX has received a status detection result packet from TX (Yes in S1509), the process proceeds to S1510.

When the RX receives a RECAL processing request packet from the TX (Yes in S1510), the RX recognizes from the second information in the RECAL processing request packet that the TX is requesting that the TX execute the RECAL processing.

In S1511, RX transmits a RECAL processing execution request packet (RP1, RP2) to TX. Having received the execution request packet from RX, TX executes the RECAL processing in S1413 based on the information in the execution request packet.

In S1414, the value of counter variable A is incremented by 1, and in S1415, if it is determined that the value of variable A is equal to or greater than a predetermined number of times (Yes in S1415), in S1416, the TX performs control to limit the transmission power or the power received by the RX.

If it is determined that the value of variable A is less than the predetermined number of times (No in S1415), the process proceeds to S1405, and the TX continues transmitting power. If the RX receives a packet for controlling to limit the transmission power from the TX (Yes in S1512), the process proceeds to S1513, and executes control to limit the power received by the RX.

In the flowcharts of Figures 14 and 15, the function of counting the number of times the RECAL process is executed is realized in S1413 and S1414, but it may be realized in other processing positions. For example, the processing from S1413 to S1415 may be executed after S1410 or S1411. Also, the processing from S1413 to S1415 may be executed after a positive (Yes) determination result is obtained in S1407 (before S1408).

The reason for this is that even if the processes from S1413 to S1415 are executed at the above-mentioned processing positions, the TX will recognize that the subsequent operation at that point will cause it to deviate from the CP or the line segment that was interpolated between the CPs in a state where there is no abnormality.

Here, we will explain the method of determining the GP related to the transmission power of the TX or the receiving power of the RX. The control operation to limit the transmission power is carried out based on this method. There is a method in which the TX and RX negotiate in the negotiation phase or renegotiation phase to determine the GP.

The RX sends Requested Load Power information to the TX. Requested Load Power is the power that the RX requests the TX to output to the load, and is the power consumed by the RX load.

The load is the system to which power is supplied from the RX or the power receiving unit of the RX, such as the charging unit 206 of the RX or the battery 207. On the other hand, the TX has a Potential Load Power value or a Negotiable Load Power value in advance.

Potential Load Power is the maximum load power value (Highest Load Power Level) that the TX can negotiate and output (supply) to the RX load.

Also, Negotiable Load Power is the maximum load power value (Highest Load Power Level) that the TX can negotiate and output (supply) to the RX load during a specified period or under specified conditions.

If the value of Requested Load Power is smaller than the value of Negotiable Load Power, the negotiation is successful. TX and RX set the value of Requested Load Power as the value of GP and store it in memory.

In other words, TX receives the Requested Load Power value from RX, and if that value is less than the Negotiable Load Power value, it sends an ACK positive response to RX.

The TX and RX set the Requested Load Power value as the GP value and store it in memory. The TX also receives the Requested Load Power value from the RX, and if that value is greater than the Negotiable Load Power value, it sends a negative acknowledgement NAK to the RX.

The RX reduces the value of Requested Load Power and again sends information indicating the value of Requested Load Power to the TX. The RX repeats this process until it receives an ACK acknowledgement from the TX.

When the RX receives an ACK acknowledgement from the TX, the TX and RX set the Requested Load Power value as the GP value and store it in memory.

By setting the GP value below a specified value, the TX's transmission power and the RX's receiving power can be reduced. To do this, the TX sets the Potential Load Power or Negotiable Load Power below a specified value.

Alternatively, the RX sets the value of Requested Load Power to a predetermined value or less. In this disclosure, when the TX requests the RX to reduce the TX transmission power or the RX receiving power, the TX or the RX performs the above operation.

Alternatively, if the RX requests the TX to reduce the TX transmission power or the RX receiving power, the TX or RX will perform the above action.

Also, by setting the GP value to a specified value or higher, the transmission power of the TX and the receiving power of the RX can be increased. To do this, the TX sets the Potential Load Power or Negotiable Load Power to a specified value or higher.

Alternatively, the RX sets the value of Requested Load Power to a predetermined value or more. In this disclosure, when the TX requests the RX to increase the TX transmission power or the RX receiving power, the TX or the RX performs the above operation.

The status detection methods include the Q-value measurement method, the waveform attenuation method, the coupling status index measurement method, foreign object detection processing based on temperature, and foreign object detection processing based on the current flowing through the power transmitting antenna. In this case, the method for determining the possibility (probability) of a TX status abnormality is explained below.

For example, suppose that the TX executes one of the state detection methods and determines that the state is <State 3> or <State 4>. In this case, the TX sets a threshold value to be used in the subsequent state detection methods. The threshold value is set based on the physical quantity measured when the state detection method is executed and it is recognized that the state is <State 3> or <State 4>.

In other words, when TX determines that it has entered <State 3> or <State 4>, it makes a decision about <State 1> to <State 4> based on information about the amount and direction (positive or negative) of departure from the measured physical quantity.

In this embodiment, the above-mentioned state detection method is executed, and if it is determined that there is a "high possibility of a state abnormality" or a "very high possibility of a state abnormality", a RECAL process is executed. If the RECAL process is executed a predetermined number of times or more, control is performed to limit the TX transmission power or the RX receiving power.

[Third embodiment]
Next, a third embodiment will be described. In this embodiment, when the TX executes the state detection method and judges that "there is a high possibility of a state abnormality" or "there is a very high possibility of a state abnormality" at least once, the control described in the second embodiment is performed.

Then, the TX executes the status detection method again, and the control that is performed when a predetermined condition indicating that the device status has improved is met is described. The operation of the TX is described with reference to Figures 14, 17, and 18, and the operation of the RX is described with reference to Figure 15.

The TX executes the status detection method, and if it determines that "there is a high possibility of a status abnormality" or "there is a very high possibility of a status abnormality", it performs the control shown in the second embodiment. The operations up to this point correspond to the processing of S1401 to S1413 in FIG. 17, and a description of these will be omitted.

In S1505 of FIG. 15, RX determines whether to request TX to execute the state detection method. If a certain condition is met, RX decides to request TX to execute the state detection method described above (Yes in S1505) and proceeds to S1506.

Then, in S1506, the RX transmits a request packet to the TX to execute the status detection method. On the other hand, if the predetermined condition is not met, the RX decides not to request the TX to execute the status detection method (No in S1505) and continues receiving power. The predetermined condition is as explained in the second embodiment.

After S1413 in FIG. 17, the process proceeds to S1801 in FIG. 18, where the TX determines whether or not it has received a packet requesting execution of the state detection method from the RX (FIG. 15: S1506). If the TX has received a packet requesting execution of the state detection method from the RX (Yes in S1801), the process proceeds to S1802.

If the TX does not receive a request packet for execution of the state detection method from the RX (No in S1801), the TX continues power transmission and the determination process of S1801 is executed repeatedly.

In S1802, the TX executes the state detection method. Note that the timing for executing the state detection method may be determined by the TX, not by the RX. If the TX determines that the above-mentioned predetermined conditions are satisfied, it may execute the state detection method.

The TX measures physical quantities related to the TX and compares the measurement results with thresholds to determine whether or not a status abnormality exists. In this embodiment, when the TX executes a status detection method, the TX determines the possibility (probability) of a status abnormality in stages.

The determination of the possibility (probability) of a status abnormality is as explained in the second embodiment. After S1802, the process proceeds to S1803.

In S1803, the TX determines whether or not there is a possibility of a status abnormality as a result of executing the status detection method. For example, a determination result of "possibility of status abnormality" corresponds to the case where the above-mentioned <Status 3> or <Status 4> is detected.

If it is determined that there is a possibility of a status abnormality (Yes in S1803), the process proceeds to S1408 from node B in FIG. 18 via node B in FIG. 14. Node B in FIG. 14 is the node that is connected after the determination result in S1407 becomes Yes.

On the other hand, if it is determined that there is "no possibility of abnormal status" or that there is "low possibility of abnormal status" (No in S1803), the process proceeds to S1804. For example, a determination result of "low possibility of abnormal status" corresponds to the detection of the above-mentioned <Status 1> or <Status 2>, or the detection of the below-described <Status 5>.

In S1804, the TX determines whether it has previously determined that the state is highly likely to be an abnormal state and executed RECAL processing. If it is determined in S1804 that the RECAL processing has not previously been executed in a state where the state is highly likely to be an abnormal state (No in S1804), the TX continues transmitting power and transitions to S1801.

If it is determined that the RECAL process has been performed in a state where there is a high possibility of a status abnormality (Yes in S1804), the process proceeds to S1805. In S1805, the TX determines whether or not <Status 5>, which will be described later, has been detected.

<State 5> is a state that satisfies a predetermined condition that indicates that the device condition has improved. For example, it is a state in which a foreign object that was between the TX and RX has been removed. If it is determined in S1805 that <State 5> has not been detected (No in S1805), the TX continues transmitting power and the process proceeds to S1801.

For example, the determination result "<State 5> was not detected" corresponds to the case where the above-mentioned <State 1> or <State 2> is detected. Also, if it is determined that <State 5> has been detected (Yes in S1805), the process proceeds to S1806.

The order of steps S1804 and S1805 may be reversed. If RECAL processing was performed in the past when there was a high possibility of an abnormal state, a CP or a line segment that interpolates between CPs is created.

Therefore, for example, if it is determined in S1805 that <State 5> has been detected, then it is necessary to execute the RECAL process. The reason for this is that unless a line segment that performs CP or interpolation between CPs is created when the device's condition has improved (a condition in which the possibility of an abnormal condition is low), it will be impossible to perform highly accurate state detection thereafter.

The processing from S1806 onwards is for executing the RECAL processing. In S1806, the TX transmits the ATN to the RX. In S1507 of FIG. 15, if the RX does not receive the ATN transmitted by the TX (No in S1507), the RX continues receiving power and waits until it receives the ATN.

If the RX receives the ATN sent by the TX (Yes in S1507), the process proceeds to S1508. In S1508, the RX sends a packet to the TX that allows the TX to send a Data packet.

The packet in question is a DSR/poll packet or a DSR/poll data packet as defined by the WPC standard.

In S1807, the TX determines whether or not it has received the DSR/poll packet or DSR/poll data packet sent by the RX. If the TX has not received the packet (No in S1807), it continues transmitting power and waits until it receives the packet.

Then, when TX receives the packet from RX (Yes in S1807), it proceeds to processing in S1808. In S1808, TX transmits to RX a status detection result packet that includes information indicating the execution result of the status detection method. Next, in S1809, TX transmits to RX a RECAL processing request packet that includes information requesting RECAL processing.

In this embodiment, the control described in the second embodiment is performed when it is determined that "there is a high possibility of a status abnormality" or "there is a very high possibility of a status abnormality" at least once. After that, a state that satisfies a predetermined condition indicating that the device's status has improved is detected.

This state is called <State 5>. For example, this is the state in which a foreign object that was between TX and RX has been removed. <State 1> and <State 2> can occur even if a foreign object is present between TX and RX (because when a foreign object is present, the threshold value CP for judgment and the line segment that interpolates between the CPs are created).

In contrast, <State 5> corresponds to a state in which the cause of the abnormal condition no longer exists (there is no abnormal condition, or the possibility of an abnormal condition is low). The method for detecting <State 5> will be described later.

When <State 5> is detected, the TX transmits a state detection result packet including the following first information to the RX.
The first information includes information indicating the state detection method that was executed and information indicating that the current state is <State 5>.

Furthermore, if <State 5> is detected, then TX transmits a RECAL process request packet including the following second information to RX:
The second information includes information requesting execution of a RECAL process based on at least one of the Power Loss method, the waveform decay method, and the binding condition index measurement method, and information requesting execution of the first or second RECAL process.

Alternatively, if <State 5> is detected, the TX may transmit a state detection result packet including the following first information to the RX in S1808 of FIG.
The first information includes information indicating the state detection method that was executed and information indicating that the current state is <state 1>.

When <State 5> is detected, the RX can recognize that <State 5> has been reached by receiving a RECAL processing request packet and a state detection result packet from the TX, which contain the above-mentioned specified information.

The TX may transmit the above-mentioned first and second information to the RX in the same packet. This allows the TX and RX to quickly and appropriately execute corresponding control when it is determined that "there is a status abnormality" or "there is a high possibility of a status abnormality."

When this determination is made, the TX performs the control described in the second embodiment and executes the RECAL process. In other words, when <State 3> or <State 4> is detected, a CP or a line segment that has been interpolated between CPs is created.

If <Status 5> is subsequently detected, it is highly likely that the condition has improved or the abnormal condition has disappeared. Therefore, the RECAL process is executed due to the change in condition.

The condition detection method can be performed based on a CP or a line segment interpolated between CPs in a state where the condition has improved or where there is a high possibility that the abnormal condition has disappeared, making it possible to detect the condition with higher accuracy.

In FIG. 15, RX receives a status detection result packet from TX (Yes in S1509), and receives a RECAL processing request packet (Yes in S1510). RX recognizes that a request to execute a RECAL has been made based on the second information in the RECAL processing request packet. Then, RX transmits RECAL processing execution request packets (RP1, RP2) to TX (S1511).

In S1810 of FIG. 18, TX receives a RECAL processing execution request packet (RP1, RP2) from RX. In S1811, TX executes RECAL processing based on the information in the execution request packet. Then, in S1812, the series of processes ends.

Next, the detection method for <State 5> will be described for each state detection method.
When the state detection method is the Q value measurement method

The TX is assumed to have set a first threshold value when executing the Q-value measurement method. In this case, the TX sets a new second threshold value for detecting <State 5> in addition to the first threshold value set for detecting an abnormal state.

The TX determines that the state is <State 5> when the measured Q value is greater than the second threshold value. Alternatively, the TX stores in memory the Q value measured when <State 1> or <State 2> is detected. The TX then calculates the difference between the Q value measured when the state detection method is executed and the stored Q value.

If the difference value is within a predetermined value, it is determined that <State 5> has been reached according to the difference value. Alternatively, the TX stores in memory the Q value measured when <State 3> or <State 4> is detected.

Then, the TX compares the Q value measured when the state detection method was executed with the stored Q value (memorized value). If the measured Q value is higher than the stored value and the difference between the measured value and the stored value is equal to or greater than a predetermined value, it is determined that the state has reached <State 5> depending on the value of that difference.

When the status detection method is the Power Loss method, the TX performs the control described in the first embodiment and executes the RECAL process when it determines that "there is a high possibility of a status abnormality" or "there is a very high possibility of a status abnormality."

In other words, when <State 3> or <State 4> is detected, a CP or a line segment that interpolates between CPs is created, and the Power Loss method is executed using a threshold value that is set based on that.

The Power Loss method is executed again in the above state, and the power loss due to the abnormal state (Ploss_FO) calculated by the TX is assumed to be a first value. The power loss due to the abnormal state calculated by the TX is assumed to be smaller than the first threshold value based on the power loss derived based on the CP or the line segment interpolated between the CPs.

In this case, it is determined to be in <State 1> or <State 2>. TX determines that there is no state change, or that there is a high possibility that there will be no state change, and does not transmit a packet including the first to third information items described above to RX.

Alternatively, if the TX detects <State 2>, it may request the RX to execute a state detection method other than the Power Loss method. Also, it is assumed that the Power Loss method is executed again in the above-mentioned state, and the power loss due to the abnormal state (Ploss_FO) calculated by the TX is a second value.

The second value is assumed to be a positive value (power loss). The power loss due to the abnormal state calculated by the TX is assumed to be greater than the first threshold value based on the power loss derived based on the CP or the line segments interpolated between the CPs. In this case, it is determined to be in <State 3> or <State 4>, and the same control as in the second embodiment is performed.

On the other hand, assume that when <State 5> is detected, the Power Loss method is executed based on the threshold set in <State 3> or <State 4>. The Power Loss method is executed again in the above-mentioned state, and the power loss due to the abnormal state (Ploss_FO) calculated by the TX is the third value.

In this case, the threshold value using the Power Loss method has already been set in <State 3> or <State 4>. The TX executes the Power Loss method to calculate the power loss due to the abnormal state. If the current state becomes <State 5>, for example, there is a possibility that the third value will become a negative value.

The reason for this is that the threshold that has already been set is the threshold for <State 3> or <State 4>. In other words, when the Power Loss method is executed in <State 5>, the power loss due to the abnormal state calculated by the TX is reduced because the abnormal state is no longer present.

In order to detect <State 5>, the TX sets a second threshold using the CP or a line segment interpolated between CPs. The second threshold is different from the first threshold, and the second threshold is smaller than the first threshold. If the value of power loss due to abnormal status calculated by the TX is smaller than the second threshold, it is determined to be in <State 5>.

Another method is to compare the first value with the third value and make a judgment based on the comparison result. The first value is the value of power loss due to an abnormal state calculated by the TX when it is judged to be in <State 1> or <State 2>.

In contrast, the third value is the value of power loss due to an abnormal state calculated by the TX when it is determined to be in <State 5>. The third value is smaller than the first value. If there is a difference between the third value and the first value that is equal to or greater than a predetermined value, it is determined that <State 5> has occurred depending on the value of that difference.

In other words, the TX stores a first value in advance, and if the power loss due to an abnormal state (Ploss_FO) calculated when the state detection method is executed is smaller than the first value and there is a difference of a predetermined value or more, it determines that the state has entered <State 5> according to the value of that difference.

Alternatively, if the power loss due to the abnormal state (Ploss_FO) is smaller than the first value and is a negative value, the TX determines that it has entered <State 5> according to the difference value.

Alternatively, if the power loss due to the abnormal state (Ploss_FO) is smaller than the first value, there is a difference of a predetermined value or more, and the value is negative, the TX determines that it has entered <State 5> according to the difference value.

When the state detection method is the waveform decay method, the TX sets the threshold value based on the fourth threshold setting method when executing the waveform decay method. In other words, the threshold value is determined based on the result of the CAL process of the waveform decay method.

In this case, the same procedure can be used as in the Power Loss method described above. The TX sets a threshold for detecting <State 5> using the CP or a line segment that has been interpolated between CPs.

If the value of the waveform attenuation index calculated by the TX (referred to as the Q value) is greater than the threshold, it is determined to be in <State 5>. Alternatively, the TX stores in memory the value of the waveform attenuation index calculated when it is determined to be in <State 1> or <State 2>.

Then, the value of the waveform attenuation index calculated by the TX when executing the state detection method is assumed to be greater than the stored value of the waveform attenuation index. If the difference between the values of these waveform attenuation indexes is equal to or greater than a predetermined value, it can be determined that <State 5> has been reached according to the value of that difference.

Alternatively, the TX sets a threshold based on the first threshold setting method, the second threshold setting method, or the third threshold setting method when executing the waveform attenuation method. The TX newly sets a second threshold for detecting <State 5>, separate from the first threshold set based on the first threshold setting method, the second threshold setting method, or the third threshold setting method.

If the value of the waveform attenuation index calculated by the TX (referred to as the Q value) is greater than the second threshold, it is determined to be in <State 5>. Alternatively, the TX stores in memory the value of the waveform attenuation index calculated when it is determined to be in <State 1> or <State 2>.

When the state detection method is the combined state indicator measurement method, the TX is assumed to set a threshold based on the third threshold setting method when performing the combined state indicator measurement method.

This threshold is determined based on the results of the CAL process of the binding state index measurement method. In this case, it can be performed in the same way as in the case of the power loss method described above. TX sets the threshold for detecting <State 5> using CP or a line segment that has been interpolated between CPs.

If the value of the coupling state index (coupling coefficient) is greater than the threshold, the TX determines that the state is <State 5>. Alternatively, the TX stores in memory the value of the coupling state index calculated by the TX when the state is determined to be <State 1> or <State 2>.

After that, suppose that the value of the binding state index calculated by the TX when executing the state detection method becomes greater than the stored value of the binding state index. If the difference between the values of these binding state indexes is equal to or greater than a predetermined value, it can be determined that <State 5> has been reached according to the value of that difference.

Alternatively, the TX sets a threshold based on the first threshold setting method, the second threshold setting method, or the fourth threshold setting method when performing the binding state indicator measurement method. The TX sets a new second threshold for detecting <State 5> in addition to the first threshold set based on the first, second, or fourth threshold setting method.

If the value of the coupling state index (referred to as the coupling coefficient) calculated by the TX is greater than the second threshold, it is determined to be in <State 5>. Alternatively, the TX stores in memory the value of the coupling state index (referred to as the k value) calculated when it is determined to be in <State 1> or <State 2>.

Then, the value of the binding state index calculated by the TX when executing the state detection method is assumed to be greater than the stored binding state index value. If the difference between the values of these binding state indexes is equal to or greater than a predetermined value, it can be determined that <State 5> has been reached according to the value of that difference.

When the state detection method is a foreign object detection process based on temperature, the TX is assumed to have set a first threshold value when executing the foreign object detection process based on temperature. The TX newly sets a second threshold value for detecting <state 5> in addition to the first threshold value set for detecting an abnormal state.

If the measured temperature value becomes smaller than the second threshold, the TX determines that the state is <State 5>. Alternatively, the TX stores in memory the measured temperature value when the state is determined to be <State 1> or <State 2>.

After that, when the TX executes the state detection method, the difference between the measured temperature value and the stored temperature value is assumed to be within a predetermined value. In this case, it can be determined that the state has reached <State 5> depending on the value of that difference.

Alternatively, the TX stores in memory the temperature measurement value when it is determined to be in <State 3> or <State 4>. Thereafter, when the TX executes the state detection method, the temperature measurement value is assumed to be lower than the stored temperature value.

In this case, if the difference between those temperature values is equal to or greater than a predetermined value, it can be determined that <State 5> has been reached depending on the value of that difference.

When the state detection method is a foreign object detection process based on a current flowing through the power transmitting antenna, the TX is assumed to set a first threshold value when executing a foreign object detection process based on a current flowing through the power transmitting antenna.

The TX sets a new second threshold for detecting <State 5> in addition to the first threshold set for detecting abnormal conditions. If the value of the current flowing through the power transmitting antenna measured by the TX becomes smaller than the second threshold, it is determined to be in <State 5>.

Alternatively, the TX stores in memory the value of the current flowing through the power transmitting antenna measured by the TX when it is determined to be in <State 1> or <State 2>. Thereafter, the difference between the value of the current flowing through the power transmitting antenna measured by the TX when the state detection method is executed and the stored current value is within a predetermined value.

In this case, the TX determines that it has entered <State 5> based on the value of the difference. Alternatively, the TX stores in memory the value of the current flowing through the power transmitting antenna that it measures when it determines that it is in <State 3> or <State 4>.

After that, the value of the current flowing through the power transmitting antenna measured by the TX when executing the state detection method is assumed to be smaller than the stored current value. If the difference between these current values is equal to or greater than a predetermined value, the TX determines that it has entered <State 5> according to the difference value.

FIG. 19 is a sequence diagram showing the operation of the power transmitting device and the power receiving device in this embodiment. The differences from FIG. 16 will be explained. TX executes the first RECAL process, and then RX decides to request TX to execute the status detection method. RX sends an execution request packet of the status detection method to TX.

The TX that receives the execution request packet executes the status detection method specified by the RX. Assume that the TX determines that the possibility of a status abnormality is low. The TX determines that it has previously executed RECAL processing in a state where the possibility of a status abnormality was high.

The TX determines that it has detected <State 5>. The TX then sends an ATN to the RX, and the RX sends a DSR/poll packet or a DSR/poll data packet to the TX.

The TX sends a status detection result packet to the RX, and a RECAL processing request packet. The RX sends a RECAL processing execution request packet to the TX, and the TX that receives the execution request packet executes the RECAL processing.

In this embodiment, after it is determined that there is a "high possibility of an abnormal condition" or a "very high possibility of an abnormal condition" and the control shown in the second embodiment is performed, appropriate control can be performed if it is detected that the condition of the device has improved.

[Applications of the present disclosure]
A part (or in some cases, the whole) of the configuration in the above embodiment may be replaced with another configuration having a similar function, or may be omitted, or another configuration may be added. In addition, the present invention is not limited to the WPC standard, and can be applied to various standards.

The power transmitting device and the power receiving device may be, for example, an image input device such as an imaging device (still camera, video camera, etc.) or a scanner, or an image output device such as a printer, copier, or projector.

It may also be a storage device such as a hard disk device or a memory device, or an information processing device such as a personal computer (PC), smartphone, or tablet device.

The power receiving device of the present disclosure may also be an information terminal device. For example, the information terminal device has a display unit (display) that displays information to a user and is supplied with power received from the power receiving antenna.

The power received from the power receiving antenna is stored in a power storage unit (battery), and power is supplied from the battery to the display unit. In this case, the power receiving device may have a communication unit that communicates with other devices different from the power transmitting device. The communication unit may be compatible with communication standards such as NFC communication and the fifth generation mobile communication system (5G).

The power receiving device of the present disclosure may also be a vehicle such as an automobile. For example, an automobile, which is a power receiving device, may receive power from a charger (power transmitting device) via a power transmitting antenna installed in a parking lot. Also, an automobile, which is a power receiving device, may receive power from a charger (power transmitting device) via a power transmitting antenna embedded in the road.

Such automobiles supply the received power to a battery. The power from the battery may be supplied to a driving part (motor, electric part) that drives the wheels, or may be used to drive sensors used for driving assistance or a communication part that communicates with external devices.

In other words, in this case, the power receiving device may have, in addition to the wheels, a battery, a motor or sensor that is driven using the received power, and even a communication unit that communicates with devices other than the power transmitting device. Furthermore, the power receiving device may have an accommodation unit for accommodating a person.

For example, the sensor may be a sensor used to measure the distance between the vehicle and other obstacles. The communication unit may be compatible with the Global Positioning System (Global Positioning Satellite, GPS), for example.

The communication unit may be compatible with communication standards such as the fifth generation mobile communication system (5G). The vehicle may be a bicycle or a motorcycle.

The power receiving device of the present disclosure may also be an electric tool, a home appliance, etc. These devices that are power receiving devices may have a battery as well as a motor that is driven by the received power stored in the battery.

These devices may also have a notification means for notifying the remaining battery level, etc. Furthermore, these devices may have a communication unit for communicating with other devices other than the power transmission device. The communication unit may be compatible with communication standards such as NFC and the fifth generation mobile communication system (5G).

The power transmission device of the present disclosure may also be an in-vehicle charger that transmits power to a mobile information terminal device, such as a smartphone or tablet, that supports wireless power transmission inside the vehicle. Such an in-vehicle charger may be installed anywhere inside the vehicle.

For example, the car charger may be installed in the car's console, instrument panel, or between the passenger seats, in the ceiling, or in the door. However, it is best not to install it in a location that interferes with driving.

In addition, while the power transmission device has been described as an example of an on-board charger, such chargers are not limited to those installed in vehicles, and may also be installed on transport vehicles such as trains, airplanes, and ships. In this case, the charger may also be installed in a position between passenger seats, on the ceiling, or in the door.

Also, a vehicle such as an automobile equipped with an on-board charger may be the power transmitting device. In this case, the power transmitting device has wheels and a battery, and supplies power to the power receiving device via a power transmitting circuit unit and a power transmitting antenna using the power of the battery.

[Other embodiments]
The present disclosure can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or storage medium, and having one or more processors in a computer of the system or device read and execute the program.

It may also be possible to implement this using a circuit (e.g., an ASIC) that implements one or more functions. Also, some of the processing described with reference to the flowcharts in this disclosure may be implemented using hardware.

For example, a specific compiler can be used to automatically generate a dedicated circuit on an FPGA from a program for implementing each step. Also, a gate array circuit can be formed in the same way as an FPGA, and implemented as hardware.

According to the above embodiment, the power transmitting device determines appropriate control based on multiple state detection results and notifies the power receiving device of multiple pieces of information related to that control, allowing the power transmitting device and the power receiving device to perform more appropriate control.

This application claims the benefit of Japanese Patent Application No. 2022-191548, filed on November 30, 2022. The contents of the above Japanese patent application are incorporated herein by reference in their entirety.

Claims

A power transmitting means for wirelessly transmitting power to a power receiving device using a power transmitting antenna;
A communication means for communicating with the power receiving device;
A detection means for measuring a physical quantity related to the power transmitting device and detecting a state of the power transmitting device;
A control unit that controls the power transmitting unit and the measurement process,
The control means controls the communication means to transmit to the power receiving device a signal having information on the state detection result related to the first or second state detection and a signal having information related to a request to execute the measurement process again when the control means determines that the power receiving device should request the power transmitting device to execute the measurement process again based on information obtained when a first state detection based on the measurement process is performed and information obtained when a second state detection based on a measurement process executed after the measurement process is performed.
The power transmission device of claim 1, characterized in that, when the control means determines that there is a possibility of a status abnormality related to the power transmission device when the status detection is performed, the control means controls the communication means to send a signal having first information indicating the status detection result to the power receiving device, and the power receiving device to send a signal having second information to the power receiving device for requesting the power transmission device to perform the measurement process again, and when the communication means receives an execution request from the power receiving device requesting the measurement process to be performed again, the control means controls the execution of the measurement process again.
The power transmitting device according to claim 2 , wherein the control unit counts the number of times the re-measurement process is executed, and when the count is equal to or greater than a threshold value, performs control to limit power transmission by the power transmitting unit.
The power transmission device according to claim 3, characterized in that, in controlling to limit power transmission by the power transmission means, the control means controls the transmission power of the power transmission device or the reception power of the power receiving device to a predetermined value or less, or sends a signal to the power receiving device requesting it to send a request to stop power transmission to the power transmission device.
The power transmission device described in any one of claims 1 to 4, characterized in that when the control means determines by comparing the physical quantity measured by the detection means with a threshold value that there is a possibility of a status abnormality related to the power transmission device, it controls the communication means to send to the power receiving device a signal containing information requesting that the power receiving device send an execution request to the power transmission device to request that the measurement process be performed again.
The control means controls the communication means to transmit to the power receiving device a signal containing information requesting that the power receiving device send to the power transmitting device an execution request to request the execution of the measurement process again when the control means determines that the possibility of a status abnormality related to the power transmitting device is low by comparing the physical quantity measured by the detection means with a threshold value, or determines that the state has transitioned from a state where there is a possibility of a status abnormality related to the power transmitting device to a state where there is no or low possibility of a status abnormality, and when the re-measurement process has been performed in a state where there is a high possibility of a status abnormality related to the power transmitting device.
The power transmitting device according to claim 1, characterized in that the detection means executes a plurality of state detection methods among a state detection method based on a quality factor associated with the power transmitting antenna, a state detection method based on a difference between a transmitted power value and a received power value, a state detection method based on an index representing attenuation of a wave transmitted by the power transmitting means, a state detection method based on an index representing an electromagnetic coupling state between the power transmitting antenna and a power receiving antenna of the power receiving device, a state detection method based on a temperature of the power transmitting device or the power receiving device, and a state detection method based on a current flowing through the power transmitting antenna or the power receiving antenna.
The power transmitting device according to claim 7, characterized in that the control means executes any one of the status detection methods, transmits a signal having information on the status detection result to the power receiving device via the communication means, and then controls the communication means to transmit a signal having information requesting the power receiving device to transmit an execution request to the power transmitting device to request the measurement process to be performed again.
A power receiving unit that wirelessly receives power from the power transmitting device according to claim 1 using a power receiving antenna;
A communication means for communicating with the power transmitting device;
A power receiving device comprising: a control unit that controls the power receiving unit.
The power receiving device of claim 9, characterized in that when the communication means receives a signal having information on the status detection result and a signal having information related to a request to execute the measurement process again, the control means controls the communication means to send an execution request to the power transmitting device, requesting the power transmitting device to execute the measurement process again.
A wireless power transmission system including a power transmitting device and a power receiving device,
The power transmitting device is
A power transmitting means for wirelessly transmitting power to the power receiving device using a power transmitting antenna;
A first communication means for communicating with the power receiving device;
A detection means for measuring a physical quantity related to the power transmitting device and detecting a state of the power transmitting device;
a first control unit that controls the power transmitting unit and the measurement process;
The power receiving device is
power receiving means for wirelessly receiving power from the power transmitting device using a power receiving antenna;
A second communication means for communicating with the power transmitting device;
A second control means for controlling the power receiving means,
the first control means, when determining that the power receiving device should request the power transmitting device to execute a measurement process again based on information acquired when a first state detection based on the measurement process is performed and information acquired when a second state detection based on a measurement process executed after the first state detection is performed, controls the first communication means to transmit to the power receiving device a signal having information on a state detection result related to the first or second state detection and a signal having information on a request to execute the measurement process again;
The second control means, when the communication means receives a signal having information on the status detection result and a signal having information related to a request to execute the measurement process again, controls the second communication means to send an execution request to the power transmission device, requesting the power transmission device to execute the measurement process again.
A control method executed in a power transmitting device that wirelessly transmits power to a power receiving device, comprising:
transmitting power wirelessly to the power receiving device by a power transmitting means using a power transmitting antenna;
communicating with the power receiving device by a communication means;
a detection step of measuring a physical quantity related to a power transmission device and detecting a state of the power transmission device by a detection means;
A control step in which a control means controls the power transmitting means and controls related to the measurement process,
A control method for a power transmitting device, characterized in that in the control step, when the control means determines that the power receiving device should request the power transmitting device to perform a measurement process again based on information obtained when a first state detection based on the measurement process is performed and information obtained when a second state detection based on a measurement process performed after the measurement process is performed, the control means controls the communication means to transmit to the power receiving device a signal having information on the state detection result related to the first or second state detection and a signal having information related to a request to perform the measurement process again.
A storage medium storing a computer program for causing a computer of a power transmitting device that wirelessly transmits power to a power receiving device to execute the following steps:
transmitting power wirelessly to the power receiving device by a power transmitting means using a power transmitting antenna;
communicating with the power receiving device by a communication means;
a detection step of measuring a physical quantity related to a power transmission device and detecting a state of the power transmission device by a detection means;
A control step in which a control means controls the power transmitting means and controls related to the measurement process,
In the control process, if it is determined that the power receiving device requests the power transmitting device to perform a measurement process again based on the information obtained when a first state detection based on the measurement process is performed and the information obtained when a second state detection based on a measurement process performed after the measurement process is performed, control is performed to transmit a signal having information on the state detection result related to the first or second state detection and a signal having information related to a request to perform the measurement process again to the power receiving device via the communication means.